Manchester United manager Ole Gunnar Solskjaer insisted it is wrong to criticise Cristiano Ronaldo's work ethic as he launched a staunch defence of the Red Devils superstar.

Ronaldo was the hero again on Wednesday, scoring the match-winning goal in a thrilling 3-2 Champions League win over Atalanta, having trailed 2-0 at half-time.

The five-time Ballon d'Or winner has scored six goals in eight matches across all competitions since returning to United from Juventus, though there has been some scrutiny of the 36-year-old amid the club's struggle for form.

Ronaldo has been criticised for not working hard or defending enough and as United prepare to host bitter Premier League rivals Liverpool on Sunday, Solskjaer backed the all-time leading scorer in men's international football.

"First of all, he's fit enough to do it still. But he's played this game 500 times before," Solskjaer told Sky Sports.

"He's been in that situation so many times, and it's one of them: 'I know what [team-mate Luke Shaw] is going to do, I know where I need to be and I'm still capable of doing it'. That's key.

"He's changed his position from being a wide forward into more of a box centre forward because he knows how to score a goal, he wants to score goals. When he first came, with all the tricks and the pace, he had the hunger - and he's still got the hunger.

"He's done what every player has to do throughout his career, you have to evolve."

Solskjaer added: "When Cristiano came to us, he'd not had a proper pre-season at Juventus and you can see he's gradually getting fitter and fitter.

"Now he feels: 'I'm getting towards the level I know I can be'. Wednesday night, the focus, the physical effort, the run… he had the highest amount of sprints, the longest sprint distance, the longest high-intensity distance.

"We talk about players who run a lot, he does as much as them. If people want to criticise his work ethic, that's completely wrong. You see him running down the channels, which he has to do as a centre forward.

"He does the work that we want him to do for the team. Of course, the team, when you have a player like him, you've got to get the best out of him, but he knows he's part of the jigsaw of that team and he's been brilliant."

United – sixth in the table and four points behind second-placed Liverpool – have won just one of their last 10 Premier League meetings against the Reds (D6 L3), losing this exact fixture 4-2 last season.

Solskjaer's United shipped four goals in a home Premier League game for only the fifth time in last season's encounter with Liverpool. The last team to score four-plus goals in consecutive top-flight visits to Old Trafford was Burnley in 1961-62 (won 4-1) and 1962-63 (won 5-2).

United are without a clean sheet in any of their last nine home league matches, their longest streak without one since a run of 10 between September 1970 and February 1971.

Meanwhile, United have only picked up eight points from their last seven home Premier League matches (W2 D2 L3), winning twice as many points in their previous seven at Old Trafford (16 – W5 D1 L1).