West Brom have sent defender Joleon Lescott to an intensive American training camp in a bid to get him fit to face Everton after the international break.
The Baggies, who made an 11th summer signing at the weekend with the arrival of Argentina winger Sebastian Blanco, are desperate to get all their new-boys fit to line up against the Toffees on September 13.
And they have sent Lescott to fitness specialists in the United States for a week of 'pre-season' training designed to bring forward the former Wolves and England man's Albion debut.
Lescott, Blanco, Silvestre Varela and Georgios Samaras are all still awaiting their first appearance in Albion colours while Cristian Gamboa, Jason Davidson, James Morrison and record signing Brown Ideye are short of fitness missing much of pre-season.
And the pressure is now on to get them ready after Irvine's depleted squad lost 3-0 at Swansea on Saturday to leave him with just two points from his first three Premier League games.
"We're in a strange situation where we have one group of players who are ready, who we can rely on in terms of fitness and who we know a lot better and another group of players who are all at different stages in terms of their fitness and their understanding of what we're doing," said Irvine.
"I would have certainly felt more confident if we had all our players here for the next two weeks but we don't because of internationals.
"We have 12 or 13 going away. Samaras and Davidson will be away. Varela, Blanco, Gamboa and Ideye will be here so we've got a few who we can work with.
"Joleon is going to go to the States to do a fitness routine there with people I know and who I've worked with before at Everton.
"There's no concern, there was just a feeling that that might be the best approach for him at this moment. The plan is that he will come back from that absolutely ready to go and we can have him for the following week."