Manchester United manager Ole Gunnar Solskjaer has admitted he will find it difficult to keep his players fully fit during a hectic schedule over Christmas and the New Year.

United face Sheffield United at Bramall Lane on Thursday to kick off a run of six games in 16 days and Solskjaer said he will be forced to rotate his squad to keep key players fresh.

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"We have to be mindful of little strains and niggles and decisions have to be made," Solskjaer told a news conference on Wednesday.

"From kickoff against Sheffield United to kickoff against Aston Villa [on Jan. 1], it is 16 days, so it's going to be very tight. It will be hard to have everyone 100% sharp."

Solskjaer is set to be without Edinson Cavani against Sheffield United with the striker still recovering from the injury which ruled him out against RB Leipzig and Manchester City.

Defenders Phil Jones and Marcos Rojo are also sidelined but should be fit again in January.

"Edinson has done well in his rehab," Solskjaer added. "We still have to make the decision if we should risk him. It is a little bit to risk him too early, I'd doubt him to be available to pick [against Sheffield United].

"Marcos has just felt a niggle in his calf again. He worked really hard to come back, played for reserves, got a knock, worked hard again and hopefully he's back in January. Phil should be ready by January and Sergio [Romero] has been training hard as well."

United will go to Bramall Lane ninth in the table but victory over the Premier League's bottom team would propel them above Chelsea, who lost to Wolves on Tuesday.

Manchester City also dropped points at home to West Brom this week and Solskjaer has warned his players that Sheffield United pose a threat despite picking up just one point all season.

"I think it is a sign of the Premier League, the quality of the so-called lesser teams," he said. "There are no easy games in the Premier League. The top teams the last few seasons have had a knack of winning tight games instead of drawing them."