Julian Alvarez played a starring role to help Manchester City come from behind to beat Red Star Belgrade 3-1 as they began their Champions League defence at the Etihad on Tuesday.

The visitors’ goal had been shot at a lot before Osman Bukari scored in the last second of the first half to surprise Pep Guardiola’s team.

But Alvarez kept up his great start to the season by tying the game just two minutes after the break.

Omri Glazer, the custodian for Red Star, flapped at Alvarez’s free kick, which helped the Argentine get the ball into the far corner.

Rodri scored the last goal with a calm finish with 17 minutes left.

“If we scored two goals early in the beginning it would’ve been completely different,” said Guardiola, who was frustrated at his side’s finishing after having 22 shots in the first-half alone.

“Having 22 shots on goal means you are playing really good. It has to be the responsibility of the people in front to score the goals.”

After City won the treble last season and started the new Premier League season with five wins out of five, most people thought Red Star would be easy pickings.

But the English champions made things hard for themselves, and Glazer saved the day before halftime for the Serbian giants.

Erling Haaland hasn’t scored in four straight Champions League games. He was upset with himself after he hit the crossbar with a header from right in front of the goal.

Then, Phil Foden pointed an even easier chance in the direction of Glazer.

Due to injuries, City could only use eight of the 12 substitutes they were allowed, and two of those were goalkeepers.

And just before halftime, Jeremy Doku had to replace Bernardo Silva, which could be another injury problem for Guardiola.

In the first 45 minutes, Red Star barely left their own half, so City was shocked when Bukari came from behind and finished confidently past Ederson.

The offside flag briefly stopped the Ghanaian from being happy, but a VAR check showed that Ruben Dias had played him onside.

After the break, City got right back to work to make sure that was the only surprise of the night.

Haaland may not have been very good in front of goal, but the Norwegian’s smart pass let Alvarez score the equaliser by going around Glazer.

“We conceded an early goal (in the second-half) and after that it was difficult to maintain the pace, because we never play at this pace in our league,” said Red Star coach Barak Bakhar. “We learned a lot from this match.”

All of Glazer’s good work was then forgotten when his misplaced punch just helped Alvarez’s free kick go into the top corner.

Kevin De Bruyne’s long-term injury has made it possible for Alvarez to start more often up front instead of having to compete with Haaland.

The 23-year-old is doing well in his second season playing football in England. He has scored four goals in seven games.

“Every single game he is working, scoring goals, making assists,” added Guardiola.

Rodri was the hero for City when they finally won their first European title by beating Inter Milan 1-0 in Istanbul in June. The Spaniard is getting into the good habit of scoring important goals, which is a good thing.

The midfielder had a lot of space on the edge of the area, and he took advantage of it by curling a shot into the far corner. This gave his team all three points.