Make that 18 goals in the Premier League for the Portugal superstar after he converted a penalty that he earned himself in a 3-0 victory over Brentford on Monday evening.

Bruno Fernandes, with his 10th goal of the campaign, and Raphael Varane were the other scorers as United saved one of their best performances of the season for their final home game.

"I think tonight we probably showed one of our best performances in the last six months in possession of the ball," United interim manager Ralf Rangnick said.

The victory kept alive -- at least mathematically -- sixth-placed United's slim hopes of finishing in the top four and qualifying for next season's Champions League.

United, though, have only two games remaining and are five points behind fourth-placed Arsenal and three adrift of Tottenham, with both rivals still having four matches to play.

Ronaldo, who has netted in each of his past four games, is third on the league's goal scoring list behind only Liverpool's Mohamed Salah (22) and Tottenham's Son Heung-min (19).

Ragnick backing the 37-year-old to return next season, unlike some of his current teammates.

United fans gave standing ovations to departing veterans Nemanja Matic and Juan Mata as they were substituted on their final Old Trafford appearances.

It was also the last home game in charge for interim manager Ralf Rangnick, who will be replaced by Erik ten Hag during the off-season, while Edinson Cavani made a late cameo.

"Why should he (Ronaldo) not be a player that could still be part of the squad and help the team?" Ragnick asked.

"This is a question you have to ask Erik once he's here and obviously it's also important how Cristiano sees his role and his position."

Monday marked a year since the postponement of United's home match against Liverpool, when fans made clear their anger at the ownership of the Glazer family in the wake of the European Super League debacle.

Supporters have protested at each of United's final three home games and the anti-Glazer sentiment was apparent before and during the victory against Brentford.

Fernandes opened the scoring in the ninth minute when he crashed home a volley from Anthony Elanga's ross.

Ronaldo won a penalty when he was bundled over in the box by Rico Henry on the hour mark and he made no mistake from 12 yards.

Varane then hooked home a deflected third from a corner in the 72nd for his maiden United goal.

Australian Associated Press