Williams in last chance Lions saloon

Winger knows he must seize chance tonight or his touring career will be over

Ian McGeechan describes it as the "fourth Test – certainly the toughest game of the trip, outside of the series with South Africa itself". Shane Williams, meanwhile, acknowledges that anything short of a vintage performance will see the curtain descend on a Lions career depressingly short of personal fulfilment. One way or another, this evening's meeting with a carefully prepared and highly talented Emerging Springboks side has an awful lot riding on it.

Williams, garlanded with the world player of the year accolade in 2008, has his eye on the left wing berth for this weekend's second Test in Pretoria. The No 11 shirt is generally assumed to be up for grabs as a result of Ugo Monye's failures on the finishing front in Durban last Saturday – failures that did not impress McGeechan one little bit if the head coach's "massive missed opportunity" remark is anything to go by. The complication? Luke Fitzgerald of Ireland is also chasing the place. The game within a game at Newlands tonight will be fascinating.

"This is my last Lions tour, and if I don't play as well as I can now, this will be my last Lions game," admitted Williams, the folk-hero finisher from Swansea. "I don't want to go home feeling I haven't given it my all, so this is Last Chance Saloon time for me. Have I been trying too hard on this trip? That might be part of it. But I'll have to go looking for work in this match because so far, I haven't been involved as much as I'd have liked." Then he ventured the opinion that "I haven't got my balls in my hands often enough" before having a rethink and trying the sentence again.

McGeechan was scathing about the chances that slipped away from his side in the opening Test. "I didn't need to watch the video to know where we missed our opportunities, because it was pretty obvious during the game," he said. But Williams stopped well short of condemning Monye for his profligacy. "I'm not here to criticise the finishing," he said. "Ugo was unlucky. The first time he went close, Jean de Villiers made a tremendous effort to stop him scoring. The second time, the ball was dislodged by the tackler. That's happened to all of us. I like to think of myself as a finisher; it's what I'm paid to do. But I'm not going to sit here and tell you I'd have scored those tries."

Even so, McGeechan is looking long and hard at the Test position, and must be at least half-tempted to gamble on Williams, given the Welshman's recent record of giving Springbok wing Bryan Habana all the trouble he can handle. "I saw Bryan after the Test and told him how gutted I was not to have been involved," Williams said. "He told me: 'Never mind, we might meet next week.' I'd love that to happen, because as a player, you come on these tours to make the Test side. After winning the world player award, I knew this season would be difficult. But I'm a big boy now and I have to handle the pressure. If I can give this game my best shot, I still have a chance."

Ronan O'Gara, the three-tour No 10 who dropped the Grand Slam-winning goal for Ireland in Cardiff in March, will lead the side tonight, and he too believes there is a Test place available. "I'd say there are four or five spots under consideration," he said, "but I'd also say that if we don't perform as a team, none of us who go out there for this game will have a chance of playing against the Boks. The collective is more important than the individual. If we buy into each other, play for each other and show belief in each other, anything is possible."

Warming to his theme, O'Gara mounted a strong defence of Paul O'Connell, the tour captain, whose performances have provoked criticism. "I know Paul and he's unwavering in his belief," said O'Gara, who has twice played alongside his fellow Munsterman in Heineken Cup-winning sides. "I hope he gets what he deserves out of this tour, because he's a fantastic player. He needs to be appreciated."

Along with the left wing and outside-half positions, there could be a second-row place in the mix. All three candidates to break into the Test engine room – Donncha O'Callaghan, Nathan Hines and Simon Shaw – are in tonight's squad. Both Tim Payne and John Hayes, the props called in as a result of injury to others, will start the match, with Phil Vickery, who endured such a rough ride at the weekend, covering them on the bench.

Nine of the Emerging Springboks side have already faced the Lions on this tour, including the impressive Western Province flanker Duane Vermeulen.

Asked whether the tourists could have done without this fixture, McGeechan smiled wistfully and replied: "As an international coach, I'd always want to prepare my side from Saturday to Saturday, which is an advantage the Springboks currently have over us. But this is a part of being on tour with the Lions."

British & Irish Lions v Emerging Springboks

*K Earls (Munster and Ireland); S Williams (Ospreys and Wales), R Flutey (Wasps and England), G D'Arcy (Leinster and Ireland), L Fitzgerald (Leinster and Ireland); R O'Gara (Munster and Ireland, capt), H Ellis (Leicester and England); T Payne (Wasps and England), R Ford (Edinburgh and Scotland), J Hayes (Munster and Ireland), D O'Callaghan (Munster and Ireland), N Hines (Perpignan and Scotland), J Worsley (Wasps and England), M Williams (Cardiff Blues and Wales), A Powell (Cardiff Blues and Wales).

Replacements: L Mears (Bath and England), P Vickery (Wasps and England), S Shaw (Wasps and England), D Wallace (Munster and Ireland), M Blair (Edinburgh and Scotland), J Hook (Ospreys and Wales), U Monye (Harlequins and England).