Pep Guardiola says the credit for Kevin De Bruyne's free-kick against Cardiff City rests with the Belgian midfielder, with inspiration from one of his assistants.

De Bruyne opened the scoring in Sunday's 2-0 FA Cup fourth-round win with a placed free-kick from 20 yards that beat goalkeeper Neil Etheridge after going under the wall.

Guardiola had watched the Championship promotion hopefuls in the previous round against Mansfield Town and spotted that Cardiff's wall jumps on all defensive set-pieces.

But the Manchester City manager refused to take credit for De Bruyne's quick thinking after his side maintained hopes of winning a quadruple, despite Leroy Sane's injury.

"We showed them today," Guardiola said after City's victory. "My assistant – we saw the wall jump and after he decided.

"You always give the information, but I'm sorry – the talent is the talent and the credit goes to Kevin."

De Bruyne scored a similar low free-kick at home to Bournemouth in the Premier League last season. 

But the modest Belgium international played down his strike as he confirmed City are concerned about an injury to Sane that could keep the forward out for four weeks.

"They told us before the game [about the Cardiff wall jumping] and we know all the details," De Bruyne said.

"The wall was not nine metres [away] for me so it was very close so I thought it would be easier to hit it under rather than over.

"The second half was strange because they didn't want to attack us and I think it was a little bit boring for half an hour. But that helped us conserve energy for the next game.

"We knew how they played –we just tried to concentrate on our football and they caught us a few times and that is football but obviously Leroy Sane is injured now and hopefully that is not too bad."