Barcelona’s Gerard Pique (left) makes a challenge on Manchester City’s Nolito.

For Barcelona coach Luis Enrique, injuries to defenders Gerard Pique and Jordi Alba took the gloss off the Catalans’ 4-0 triumph over Manchester City as he now has to deal with their absence in their next Champions League match on November 1.

Barcelona confirmed yesterday that Pique sprained a ligament in his right ankle in the match against City and will be out for three weeks, while Alba has a left hamstring problem and will be sidelined for two weeks – meaning both will miss the trip to the Etihad Stadium.

“It’s always worrying when you lose players through injury,” Luis Enrique said.

There are three games remaining in the group stages and Barcelona, who have a perfect record and are five points clear at the top of Group C, will seal their place in the next round if they beat City on November 1.

“I’m certain we will find it difficult in Manchester,” the Barcelona coach added.

Despite Barcelona’s injury woes, the real battle in Group C is for second place.

Pep Guardiola’s City is second with four points and Borussia Moenchengladbach have three following their 2-0 win at bottom-placed Celtic, who have one point.

For Luis Enrique, the most encouraging aspect of Barca’s performance was seeing Lionel Messi complete a hat-trick in his first start following a three-week break with a groin injury.

Messi set the tone for another virtuoso performance with a storming run through the middle of City’s half before calmly dribbling past Claudio Bravo to score.

The floodgates opened once former Barca goalkeeper Bravo was sent off for handling outside the area and Messi toyed with City’s defence to smash the ball past compatriot Willy Caballero.

The five-times world player of the year sealed a second hat-trick of the season by tucking home a Luis Suarez cut-back and was tripped by Aleksandar Kolarov in the dying minutes, although Brazilian forward Neymar missed the resulting penalty.

“We saw Messi play like a kid in the school playground today,” Luis Enrique said.

“Any other player would be shaking (after coming back from injury) but if we have come to expect anything from Messi, it’s that.

“It doesn’t matter how long he’s been out for or how many games he’s missed, he has a total understanding of football. Anyone who ever doubts Messi is naive.

“Those of us lucky enough to see him train every day know what he does. He helps in every sense and he is a reference point for us, without a doubt.”

Messi’s latest exhibition had echoes of his two-goal masterpiece against Bayern Munich, managed by Pep Guardiola, in a Champions League semi-final first leg in 2015.

“Since I’ve known him he’s always done things like that and he keeps doing it,” said Guardiola, now in charge of Man. City.

“This is not the first time he’s done this, I’ve seen him do it many times live before, but you have to congratulate him.”

Messi scored a hat-trick for the second time in the Champions League this season and the seventh time in the competition.

The Argentine, who had come on as a substitute and scored one goal in Barca’s 4-0 win over Deportivo La Coruna at the weekend, wrote on his Facebook account: “What a great way to return to UEFA Champions League action with an important win, a big effort from the whole team and our fans.”

Barca are fourth in La Liga and play away to Valencia tomorrow.