Celtic manager Gordon Strachan is refusing to panic despite pre-season preparations ending with a 3-0 defeat at home to Manchester United.
Paul Scholes (right) scored a double at Celtic Park
Strachan insisted it only went to show that "their second team is far better than our second team".
"We don't just dismiss it - that would be foolish and naive and not respecting our opponents," he said.
"What we need now is for those who think they're back-up players to realise they can't be back-up players."
Celtic have won just one of their pre-season friendlies, at home to Everton.
Strachan did play an experimental line-up, with wantaway midfielder Stilian Petrov on the bench, but it was still more experienced than United's.
Stilian's been magnificent in the last couple of games
"It's asking too much of the mainstays and the names that have been bringing success to the club for the last few years," said Strachan.
"The back-up players need to really back us up.
"To be fair, that was the first time that many of them got 90 minutes. I think that affected us.
"But Iit doesn't really count until the start of the season - and we'll see what happens and we'll decide if it's affected our confidence then.
"I will tell you in about five or six weeks' time if it's a concern or not.
"Last year, we didn't score many goals in pre-season and didn't play particularly well and we won the league by 21 points."
Strachan dismissed the uncertainty presented by Portsmouth's latest bid for Petrov.
"Stilian's been magnificent in the last couple of games, his training's been fantastic so it doesn't affect me whatsoever," he said.
Strachan refused to confirm reports he is interested in Ukraine midfielder Anatoliy Timoschuk.
"We're interested in a lot of players and we're active in the transfer market, but I don't talk about players until they're here," he said.
However, Celtic did issue a statement describing as "absolute rubbish" newspaper reports claiming that the club had failed in a £2.5m bid for Espanyol striker Raul Tamudo.