McDonald has hit 25 goals for Celtic since his move from Motherwell last summer but in Europe he only found the net with his strike in qualifying against Spartak Moscow and the late winner against AC Milan at Parkhead in the group stages.

The 24-year-old Australian, formerly of Motherwell, was only a substitute against Barcelona yesterday as Celtic lost 1-0 in the Nou Camp and 4-2 on aggregate to go out of the Champions League at the last-16 stage.

However he has started all but two of Celtic's 10 European games this season, and admits he could have performed better.

McDonald told Celtic View, prior to last night's defeat: "I've been disappointed with a couple of games that we have played in Europe and I feel I can do more.

"I guess that's what makes me who I am and I will always strive to do better.

"Even if I've done well, I am always picky about my game and it's important that I keep improving as a player."