Manchester City got off to a sluggish start in their UEFA Champions League campaign, as the 2023 title winners settled for a 0-0 draw against Inter Milan on Wednesday, while Paris Saint-Germain (PSG) needed a last-minute goal to beat tournament newcomers Girona 1-0.

Pep Guardiola's Man City side have won all four of their Premier League games this season, but failed to break down Italian Serie A champions Inter in a rematch from the 2023 final.

City lost Kevin De Bruyne to injury at halftime and Phil Foden fired straight at Inter goalkeeper Yann Sommer with their best chance, while Erling Haaland was kept quiet in his pursuit of a 100th goal for the English club.

"It was a very intense game against a strong opponent," City defender Ruben Dias told TNT Sports. "We knew what was coming, they are a top team as well and they are used to winning, so we were not going to have an easy job."

Henrikh Mkhitaryan could have won it for Inter when he blazed the ball over the crossbar 15 minutes from time, allowing City to extend their unbeaten run in the competition to 24 matches, one behind the record set by local rivals Manchester United between 2007 and 2009.

It was just the second time in 42 Champions League home games under Guardiola in which City failed to score.

"Our plan was to show that we're not scared to play here," said Inter midfielder Hakan Calhanoglu.

PSG looked as if they would also have to settle for a point against European debutants Girona, who are backed by the City Football Group and maintained a dogged pursuit of Real Madrid for several months before finishing third in the Spanish La Liga last season.

A goalkeeping blunder by Paulo Gazzaniga in the 90th minute, however, allowed a crossing attempt by Nuno Mendes to squirm through his grasp and hand the French Ligue 1 champions the narrowest of victories.

"It was a difficult game, they're a team that plays well with the ball," Mendes told Canal Plus. "I was surprised (by the goal). The goalkeeper was there and it got through."

Last season's runners-up Borussia Dortmund, beaten by Real Madrid in the final, had English winger Jamie Gittens to thank as the 20-year-old came off the bench and scored twice in a 3-0 win at Brugge.

Serhou Guirassy added a stoppage-time penalty for his first Dortmund goal since arriving in the summer from Stuttgart.

Celtic began in style by thrashing Slovan Bratislava 5-1 in Glasgow, winning their opening game in the Champions League for the first time in 13 attempts.

Liam Scales' powerful header put Celtic ahead and the hosts struck again through Kyogo Furuhashi early in the second half, before Arne Engels converted a penalty to make it 3-0.

Kevin Wimmer pulled one back with a fine strike for the Slovakian champions, who advanced through four rounds of qualifying, but Celtic pulled away with further goals from Daizen Maeda and Adam Idah.

"It's a fantastic night," Celtic captain Callum McGregor told TNT Sports. "I hope the supporters enjoyed it because the managers and players did. This is the next level for the group in terms of growth and development."

Bologna drew 0-0 at home against Ukrainian club Shakhtar Donetsk in the Italian team's first-ever Champions League match. Lukasz Skorupski saved an early penalty from Shakhtar's Georgiy Sudakov.

Sparta Prague swept Red Bull Salzburg aside 3-0 with goals from Kaan Kairinen, Victor Olatunji and Qazim Laci, as the Czech champions won for the first time in the competition's main stages since 2003.