Michael Olise and Harry Kane scored as Bayern won in Glasgow, while Feyenoord earned a slim first-leg advantage against Milan.
Bayern München took a 2-1 advantage over Celtic in Glasgow, but there is all still to play for in Germany next week following a spirited fightback from the hosts in their knockout phase play-off first leg.
Elsewhere on Wednesday, Feyenoord beat Milan, Club Brugge defeated Atalanta and Benfica saw off ten-man Monaco.
On Tuesday, meanwhile, Real Madrid came from behind to beat Manchester City 3-2 in a thriller, while there were also wins for Paris Saint-Germain, Borussia Dortmund and Juventus.
THEUPDATE through UEFA.com rounds up all the Wednesday night’s action.
- Celtic 1-2 Bayern München
Harry Kane’s ferocious second-half volley – which made him the first English player to score 60 times in UEFA club competitions – gave Bayern a lead to take into next week’s return game after a 2-1 win.
Michael Olise’s left-footed drive put them in front just before the break, with Kane adding to it soon after.
A late strike from close range by Daizen Maeda leaves the tie in the balance, however, with his goal giving Celtic hope of a second-leg turnaround.
- Feyenoord 1-0 Milan
Feyenoord claimed a narrow first-leg victory following an impressive display against seven-time winners Milan.
The Eredivisie side were ahead just three minutes in when Mike Maignan was unable to hold Igor Paixão’s crisp shot after the winger had cut inside from the left flank.
The lively Brazilian midfielder was at the heart of Feyenoord’s attacking play, hitting the bar with a curling effort ten minutes before half-time and going close midway through the second period with an audacious long-range strike.
- Monaco 0-1 Benfica
Vangelis Pavlidis scored his sixth goal in five Champions League matches as Benfica beat ten-man Monaco.
The game burst into life shortly after the interval when Pavlidis outran Mohammed Salisu and chipped the ball over Monaco goalkeeper Radosław Majecki from a narrow angle.
The hosts were reduced to ten players in the 52nd minute when Al Musrati received a second yellow card, but the visitors were unable to capitalise on their numerical advantage and add to their lead.
- Club Brugge 2-1 Atalanta
Club Brugge will take a lead to Bergamo next Tuesday after a late penalty from substitute Gustaf Nilsson sealed victory over Atalanta.
Stepping up to the spot in added time, Nilsson maintained composure, placing the ball left of middle as Rui Patrício dived in the opposite direction.
The hosts had taken a first-half lead through Ferran Jutglà, who finished powerfully after controlling a cross from the excellent Chemsdine Talbi, but Mario Pašalić restored parity before the break with a towering header.