Georgios Samaras admits Celtic was "unprofessional" in its 1-1 draw against Scottish Premier League side Ross County on Saturday but blamed it on the importance of the upcoming Champions League play-off match against Helsingborg in Sweden.
The Scottish champion was not at its best against the Staggies in Dingwall and needed a late goal from
Ahead of the first game against the Swedish champion, Samaras spoke of the importance of reaching the group stages of the competition and how he thought it affected the Hoops players in the Highlands.
"Because, if you drop points in the SPL you have all season to correct things, but now, in one week, we have to play two games and we need to be focused 100% there.
"I know it is not right but I think in the game we played on Saturday, our mind was a little bit for the game tomorrow."
After the game Neil Lennon accused some of his players of "going through the motions" but the Celtic manager stopped short of concurring with Samaras' assessment.
He said: "I don't know about that. I think unprofessional is sort of the wrong word, maybe some of them had one eye on Tuesday night.
"They know the significance of the game and how big it is for themselves and everyone associated with the club."
Samaras believes Celtic now has the "maturity" to reach the group stages of European football's elite club competition.
The former Manchester City player said: "It is an important game for us, we want to play at the top level and the Champions League is the highest level in European football.
"Europa League is European football but we did that last year and I think we were a bit unlucky not to go through.
"But I think our team is more mature now and ready to go to the highest level.
"We want to raise the bar a bit higher and the aim is to be in the group stages of the Champions League."
UEFA Champions League
Arjen Robben is desperate to bring an end to his own UEFA Champions League curse when Bayern Munich plays Borussia Dortmund in Saturday evening's (Sunday morning AEST) final at Wembley.