Defence is a big question mark for France as they start their final preparations for the World Cup in Russia, but Monday's 2-0 win against Republic of Ireland showed that the fullbacks were in excellent shape, giving confidence to the whole squad.

Benjamin Mendy and Djibril Sidibe, who both suffered serious injuries this season, looked in top form at the Stade de France, showing great offensive intentions although they were not tested on their defensive skills.

Mendy only returned to action for Manchester City in mid April after a seven-month knee injury layoff, while Monaco's Sidibe came back to training earlier this month after injuring his meniscus also in mid April.

Taking them both to Russia was a gamble for France coach Didier Deschamps but their displays against Ireland showed the risk was worth taking.

"I am really surprised not because of what they showed, but let's remember that Benjamin is just back from a serious injury," said midfielder Blaise Matuidi, who was named captain as goalkeeper Hugo Lloris was rested for the night.

"Seeing him play without any apprehension, chapeau Benjamin! It's never easy to come back from a serious injury. He showed that we could rely on him," Matuidi told reporters.

Mendy tortured the Irish midfielders and defenders with regular bursts down the left flank, while Sidibe was also active on the right flank.

"We have fullbacks who like to go forward so we give them that freedom to attack," said Matuidi.

France next take on Italy on Friday in Nice before hosting the United States in Lyon on June 9.

They will then travel to Russia, where they face Australia, Denmark and Peru in Group C.