Gordon D'Arcy thought he had earned a holiday in the United States this week, after winning the Heineken Cup with Leinster and scoring for the Barbarians at Twickenham last weekend. Instead the Ireland centre arrives in Johannesburg today to bolster the Lions' flagging midfield resources.

There is no suggestion thus far that Keith Earls or Riki Flutey will not play again on tour but the management are clearly concerned that there is no certainty when either will be fit for selection. It might be a matter of days, it might be a week or more, one Lions official said, and on a ten-match tour there is precious little leeway.

Earls, the Munsterman, damaged the joints of his right shoulder against the Royal XV in Phokeng on Saturday and Flutey has fluid on the right knee after tweaking the joint late in the same game.

D'Arcy, 29 and a Lion in New Zealand four years ago, must have missed selection for the 2009 party by a whisker given his strong finish to the season. But a broken arm sustained in the 2008 RBS Six Nations Championship meant a delayed start to last season, he did not appear for Leinster until December and had to work his way into the Ireland side that ended as grand-slam champions.

He came off the bench in the first two games but rejoined Brian O'Driscoll in a familiar centre pairing for the last two, against Scotland and Wales. The momentum rolled on as Leinster headed towards their first European triumph and D'Arcy, who has 41 caps, enjoyed himself with a tryscoring appearance as the Barbarians beat an England XV 33-26 last Saturday.

Given the manner in which his 2005 tour ended (he was withdrawn from consideration for the final international against the All Blacks suffering from fatigue), D'Arcy will see this as an opportunity to make good alongside not only O'Driscoll but Luke Fitzgerald, his provincial colleague who will hope to pull on the Lions jersey for the first time against the Cheetahs in Bloemfontein on Saturday.

It is possible that Earls and Flutey will be available next week but it seems both can be discounted for Saturday, Jamie Roberts played his second game in five days against Golden Lions last night and O'Driscoll can be counted a protected species. That leaves Fitzgerald, who has played most of his rugby on the wing during the season just ended, and James Hook, who has played inside centre but whose club position is fly half.

“While the injuries are being treated by the medical team, we feel it prudent that we call up Gordon to provide us with extra cover in midfield,” Ian McGeechan, the head coach, said. “Due to the short nature of the tour, we have to be prepared for every eventuality. Gordon was on our reserve list and we had no hesitation in calling him up.”