Belgium midfielder Kevin De Bruyne has slammed the quality of Bosnia-Herzegovina's Grbavica Stadium playing surface, describing it as "unacceptable".

The Red Devils edged a seven-goal thriller in Sarajevo on Saturday evening to maintain their near-perfect record in qualifying for the 2018 World Cup.

Victory came at a cost, though, as Manchester United ace Marouane Fellaini left the field with an injury during the first half of the thrilling affair.

Speaking to reporters after the game, De Bruyne admitted that he was thankful to avoid joining Fellaini in picking up a problem of his own on the bumpy pitch.

"I was worried I'd get injured," he said. "This was unacceptable. I don't understand how we could play on such a pitch. The last time I played on such a bad pitch was when I was a seven-year-old kid."

Manager Roberto Martinez added: "The pitch in Sarajevo was below any acceptable level. It was impossible to play any tactics."

Belgium have already made certain of top spot in Group A with one match, at home to Cyprus on Tuesday, left to play.