Manchester United defender Eric Bailly will be sidelined for the foreseeable future after having knee surgery.

The 25-year-old centre-back suffered a knee injury against Tottenham during a pre-season friendly in China last week.

The initial signs were not good and Bailly may not play again in 2019, having also battled knee problems during an injury-plagued 2018-19.

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Ole Gunnar Solskjaer confirmed the news after watching his side scrape past Norwegian outfit Kristiansund 1-0 in Oslo on Tuesday.

"Eric has had an operation and will be out for four to five months," he said.

"Hopefully we'll have him back around Christmas time."

Solskjaer acknowledged his side was fortunate to post its fifth straight pre-season victory after Juan Mata went down in the penalty area in the 91st minute.

Mata appeared to make the most of little-to-no contact from Andreas Vaikla, the third goalkeeper used by Kristiansund during the match, before scoring from the spot.

"They held their own. They defended really well," Solskjaer told MUTV.

"Of course we couldn't really break them down. They defended well and their 'keepers, all three of them, they did really well. But it's one of these games that we might get in the league ... sometimes it's the 91st minute, sometimes it's the first minute.

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"The goal was very good... quality pass, great run and you're happy winning the game."

Solskjaer's son, Noah, appeared off the bench for Kristiansund in the dying stages, while the manager was flanked by his youngest son Elijah throughout the contest.

Asked if it was a proud night for his family, the United boss added: "I think so. Noah makes his debut for them in front of 28,000. It's not very often a Norwegian boy does [that]. Elijah next to me, he enjoyed it. That's what it about."

United plays AC Milan in the International Champions Cup on Saturday.