Brendan Rodgers thinks things may have been different if Lionel Messi lined up for his Celtic side on Wednesday as the Argentine scored twice in Barcelona's 2-0 win at Celtic Park.
After scoring a hat trick in Barca's 7-0 win over the Scottish champions at Camp Nou in September, Messi was once again the difference maker in Glasgow as his eighth and ninth Champions League goals of the season moved the Blaugrana into the round of 16.
Messi missed the goalless draw against Malaga on Saturday with a bug, but his return to action against Celtic demonstrated once again just how important he is to Luis Enrique's side.
Asked in his news conference if it would have been a different game if Messi had swapped sides, Rodgers said: "We would have had a big chance, no doubt.
"He shows the difference he makes. Look at the weekend's game [against Malaga]. It's different with Messi, he's a great, great player, arguably the best who's ever played football.
"When he plays in your team he makes everyone else better, so if he was playing for Celtic he would make us better.
"But, yes, he's phenomenal player, an incredible player and he's always hungry to score. His first goal comes from that run he makes, very fast. Our players will learn you can't give that space to a player of that quality."
Celtic had chances in the game but fell behind to well worked goal between Neymar and Messi.
Moussa Dembele had an opportunity to equalise in the second half, but when Luis Suarez won a penalty moments later at the other end, the home side's chances of turning things around disappeared.
"I didn't think it was penalty," Rodgers said. "I think what Luis is brilliant at around the box is provoking defenders.
"He's leaning into Emilio [Izaguirre], who is trying to fight for his space, and what Luis is clever at is he grabs hold of the defender spins around and goes to ground.
"The momentum was with us at that point. I felt that at 1-0 we were in the game, so to go to 2-0 after [Dembele] missing a header was disappointing, but the referee didn't give us much during the night.
"Looking back to the first game [against Barca] and tonight I thought we made a significant improvement. We pressed the game, were tactically very good and won the ball back.
"That extra quality, speed of movement and pass catches us out [for the first goal]. We were always in the game, but then we get punished with the penalty. At 2-0 we still fight, work, but it becomes difficult."
The loss ensured Celtic will finish last in the group, but they are odds on to qualify for the Champions League again next season and Rodgers insists they will be better prepared.
"First and foremost the challenge was to get into the Champions League," he said. "The club had gone a period of time not qualifying, so we had a huge effort in the summer, over the course of the preseason, to qualify, and this experience -- we still have one game to go -- was always going to be invaluable to us.
"If you look at the first game compared to now, we weren't fearful tonight. It is just about maintaining that standard. We have played three of the best teams in Europe in this competition and we have gradually got better with each game.
"We know the level now, it gets better every year. We have to go and try to get into it next year and each year the club is in it, it improves on and off the field -- that is our ambition."