As the end of a long season looms large, players across the British Isles and Ireland will already have one eye trained on next summer's Lions tour to South Africa.

British and Irish Lions head coach Warren Gatland will be a keen spectator as the Champions Cup and Gallagher Premiership reach their conclusions this month with plenty of tour spots up for grabs.

Ahead of what is set to be a fascinating race for selection, BT Sport considers the winners and losers from the past two months of club rugby.

Going up

Maro Itoje

Already pencilled in as a starter, the England lock's recent performances for Saracens in Europe have seen him become the leading candidate for the Lions captaincy. 

Alun Wyn Jones and Owen Farrell are Warren Gatland's most likely alternatives but Itoje's heroic displays since the restart have thrust him into pole position. 

The 25-year-old made an eye-watering 13 tackles in Dublin as Saracens upset the odds to dump four-time winners and competition favourites Leinster out of the Champions Cup.

He was a constant thorn in Leinster's side, forcing turnovers and disrupting the home side's ability to generate quick ball at the breakdown. 

The Lions know they will have to match the Springboks for physicality and few men relish the battle of attrition more than Itoje.

Itoje appeared in all three Lions Test matches back in 2017 as the tourists came from behind to secure a historic draw against the All Blacks, with the then 22-year-old one of the standout performers.

With thoughts now turning to next year’s Tour to South Africa, Itoje is once again expected to be a key figure when the Lions lock horns with the reigning world champions.

Jack Willis

He's yet to make his England debut, but the Premiership's turnover king will be on Gatland's back-row shortlist.

Wasps have gone from a mid-table side to genuine Premiership title contenders since rugby restarted and Willis has been a major part of that run of form. 

He leads the league in turnovers with 43, more than double the number managed by his nearest rival, Blair Cowan of London Irish.

BT Sport's Ugo Monye said: “Jack has been a key reason why Wasps have been flying since the restart. We can talk about Wasps’ attacking game, which has been excellent, while they also have new management and they all look to be enjoying their rugby.

“But defensively they have been very good and one of the key features in their game, what’s making them a well-rounded side is their work at the breakdown – that’s been spearheaded by Jack Willis.

“He’s such an impactful player, he has so many big moments in games that either wrestle back momentum, create momentum or encourage teammates to become better players.

"He's just been simply outstanding - in every part of his game. Whether it be carrying, lineout, defensively, but more so than anything at the breakdown. Everyone is aware of these new law interpretations and he’s adapted to them really well. It’s been a key feature of his game.

“His work rate is off the scale but he’s not just been high impact, he’s high quality in everything that he does and that for me is what separates good Gallagher Premiership Rugby players and internationals and potential future internationals.”

Gatland has an abundance of riches in the back-row position but a strong showing in the Autumn Nations Cup could see Willis play a significant role in South Africa.

Finn Russell

Gatland's wildcard? 

The European Player of the Year nominee is one of the most creative players in the northern hempisphere.

In their recent semi-final against Saracens, Racing were three points behind with four minutes remaining when Russell put in a pin-point chip over the defence to set up Juan Imhoff's winning try.

Russell has assisted seven tries in the Champions Cup this season, more than any other player, and says he is "loving" life after helping Racing 92 to the Champions Cup final and resolving his differences with Scotland head coach Gregor Townsend.

With his international future looking more secure, a strong showing in the upcoming Eight Nations tournament would make the Scotsman a must-pick selection for South Africa's fast tracks.

His ability to conjure something out of nothing could prove pivotal against the reigning world champions.

Sam Simmonds

Simmonds has spearheaded Exeter's campaign in European and domestic cup competitions this season.

The number eight is the top try scorer in the Champions Cup this season, crossing the try line on seven occasions for the Chiefs in their march to a first ever European Cup final.

He also ranks in the top three forwards for carries (92), metres (290) and defenders beaten (23) in the competition in 2019/20, earning his a deserved nomination for the European Player of the Year award. 

While the 25-year-old is in the form of life for club, international recognition has been harder to come by. 

Simmonds has won seven caps for England since making his debut against Argentina in November 2017 and scored two tries against Italy in the 2018 Six Nations.

But a knee injury meant the explosive back-row missed much of last season and was omitted from Eddie Jones' England squad for the 2020 Six Nations. 

Now fit and firing on all cylinders again, Simmonds has already proved his worth as a game-changer, will Gatland take as much convincing as Jones?

Going down

Manu Tuilagli

The centre's hopes of going on a second Lions tour hang in the balance after he was forced to undergo surgery on a torn Achilles.

When fit, the England star was being touted as one of Gatland's first names on the teamsheet.

His size, power and pace makes him the perfect fit for a South Africa side who thrive on physicality. 

The news that Tuilagi faces six months on the sidelines is a bitter blow to England and the Lions. 

The 29-year-old was at the forefront of England's best performances in recent years - including a World Cup semi-final victory over New Zealand - but Gatland may have to reconsider his midfield options.

This is the latest blow to a career dogged by serious injury over the past decade.

He missed 15 months after injuring his groin in October 2014, ruling him out of the 2015 World Cup in England.

A groin injury in May 2016 led to him missing England's summer tour to Australia and another groin injury saw him miss two months in September of that year.

Having returned from that problem, Tuilagi was sidelined for nine months after hurting knee ligaments in January 2017.

If he can return to fitness next year and prove his form, he remains an automatic pick in any Lions squad, but it's a tough ask with so much competition in the centres.

Johnny Sexton

The Ireland fly-half is hopeful of making it three Lions tours in a row next year and has made no bones about his ambitions for next summer.

"I’d be lying if I said it wasn’t something I haven’t thought a hell of a lot about," Sexton said.

"It’s the pinnacle of any northern-hemisphere player’s career, and to do it three times would be incredibly special. It would be a dream to do it again.

"But a lot needs to happen for that to happen. I need to play well for Leinster, I need to play well for Ireland, and then hopefully put my name on the shop window for that tour.

"I'd be 35, which as an out-half wouldn't be a crazy age to get picked. Obviously there are a lot of young guys coming through and staying ahead of them would be the big challenge."

The Leinster playmaker knows he will have to turn his form around if he is to force his way into Gatland's touring party after a disappointing end to the season for his club.

Head coach Leo Cullen rested his talismanic captain for the final of the Pro14 in early September with one eye on their Champions Cup showdown with Saracens but it was a decision that proved futile as Sarries upset the odds to beat the Irish province on their own patch. 

The upcoming Autumn Nations Cup tournament could have huge bearing on Sexton's Lions chances with Russell, Owen Farrell, Adam Hastings and George Ford all vying for the number 10 shirt.

Jacob Stockdale

Considered one of the best finishers in the northern hemisphere not long ago, the Ulster winger is quickly slipping out of contention for a Lions spot.

The 24-year-old has struggled to recapture his breathtaking 2018 form in the last 18 months.

With the remaining two Six Nations games against Italy and France to come next month, as well as the Autumn Nations Cup, Stockdale's international future is in the balance.

The good form of Munster wing Andrew Conway and James Lowe's impending Irish eligibility, means Andy Farrell could explore other back-three options, potentially dashing Stockdale's hopes of a Lions tour.

A sub-par performance for Ulster in their Champions Cup quarter-final defeat to Toulouse will have done the Irishman's confidence no good as he twice failed to stop Cheslin Kolbe from going over the whitewash in a 36-8 reverse in France.

"He was average at best. Sloppy ball handling, shifting on passes to people in worse positions than he was," said Irish pundit Irish rugby pundit Shane Jennings in the wake of Ulster's Champions Cup exit.

"Stockdale was poor," he added. "If you have your best player performing like that you’re not going to get anywhere. I think he needs to have a good hard look at himself."

Speaking weeks before rugby resumed competition following the suspension, Stockdale admitted there was work to be done to force his way into Gatland's thinking.

"If the team was being picked now, I don’t know if I would be picked or not. But, by the time Warren Gatland is making his selection, I want to be in a position where it’s a no-brainer that he has to have me," he said.

"That can be done in a matter of eight months, so that’s the plan anyway."

With Anthony Watson, Liam Williams, Jonny May and Jack Nowell all vying for a wing berth, Stockdale needs a solid showing on the international stage this autumn to avoid dropping out of contention.