Manager McLeish admits he will offload players if he is to make any further signings before the transfer window closes.
But the Scot is looking for defender Warnock and midfielder Ireland to show the kind of form which made them both command ?8million fees when signed from Blackburn and Manchester City respectively.
McLeish, whose side visit Fulham on Saturday, said: "We have to trade again before we can bring anyone else in.
"But there were players, don't forget, who weren't involved last season like Warnock and Ireland.
"They have trained to a very good level pre-season and it is up to these guys to show they can do it when the real deal is about to start.
"I'm not going to guarantee anyone walking into the team or tell you who is going to be playing.
"But these two guys are players Aston Villa spent a lot of money on in terms of transfer fees and wages.
"We have to try and get more out of them and the signs have been good.
"The two of them have put in a great shift in pre-season and we know what they are capable of giving. The evidence is there.
"They both played for their countries. Ireland had a marvellous season with Man City two years ago and Warnock played for England."
Villa striker Darren Bent has recovered from the shoulder problem which ruled him out of England's midweek game with Holland at Wembley before it was postponed.
Bent scored nine goals in 16 matches after his club-record ?18million move from Sunderland in January and established himself as a first-choice player for his country.
McLeish has a virtual clean bill of health for his first competitive game in charge since replacing Gerard Houllier in June.
Central defender James Collins has also shaken off the back injury which prompted his withdrawal from the Welsh squad to face Australia on Wednesday night.
Central defender Carlos Cuellar (knee) is the only absentee through injury.
Source: Team Talk
Source: Team Talk