Scott McDonald and Jan Vennegoor of Hesselink both netted in Saturday's 3-0 win over Hearts with loan star Georgios Samaras also making an impression off the bench.

He said: "It was good to put in a decent performance against Hearts before such a difficult game with Barcelona. It's such an important game."

"Georgios is a very good player. He is very big and technically gifted. Against Hearts he had a very good left foot shot that was unlucky not to go in.

"The other strikers, Vennegoor of Hesselink and McDonald, are also playing very well just now. We can score on Wednesday. It is difficult for the manager as he can only play two of them."

Donati also believes that Barcelona will be the biggest test Celtic have faced this season.

"We have beaten AC Milan at home this season but, at this moment, I think Barcelona are better than them. They are the best team in Europe now. It will be tough.

"Sure, Barcelona have a few injury problems to deal with, but what is important for us is that we concentrate on playing well ourselves. That is what we have done at home in the three other games we have played in the Champions League this season and we've won all of them."

The Italian admitted that he has also been impressed by the other January new boys Barry Robson and Andreas Hinkel.

"Some good players came during the transfer window and I think they will make sure we don't relax in the SPL and Champions League."