Pep Guardiola's men had to battle back on several occasions to fight off a resilient Celtic and were held to a 3-3 draw.
Atletico Madrid defeated Bayern Munich 1-0 in a clash of Champions League Group D leaders at the Vicente Calderon on Wednesday.
A Theo Walcott brace was enough to give Arsenal a comfortable 2-0 win over Basel at The Emirates.
Arsenal continued their fine form with a 2-0 win over FC Basel in the Champions League on Wednesday night.
Manchester City and Celtic played out a six-goal thriller at Celtic Park as they drew 3-3 in the Champions League.
Barcelona made it two Champions League wins from two tries, as they rallied to beat Borussia Monchengladbach TK on Wednesday night at Borussia Park.