Ronald Koeman believes Manchester City are capable of getting a result in Barcelona, but warned they would be quickly punished if they gave away chances.
Koeman's Everton held Pep Guardiola's side to a 1-1 draw in the Premier League on Saturday.
The result extended City's winless run to three matches ahead of their trip to Barcelona in the Champions League.
Koeman feels Guardiola's men are good enough to record victory over the LaLiga champions - but need to be wary.
"I think [City] are strong enough as a team to get a good result in Barcelona but you play against [Lionel] Messi, Neymar and [Luis] Suarez, they will score out of one chance," the Dutchman said.
"If they get four chances they will score three times I think. The quality of Barcelona is extremely high."
Koeman, a winner of numerous trophies as a player with Barca, is looking forward to Wednesday's clash.
The former Netherlands international said the two teams' possession-based styles would make for a fascinating encounter.
Koeman said: "They will also have the ball and I think it is the best game you can watch between the philosophy of two teams and it is a really high standard of football.
"I'm really looking forward to seeing that."