City need all three points and take the lead in the Premier League title race.

The champions, who are two points behind league leaders Liverpool, play their game in hand at sixth-placed United, with the home side looking to make up for lost ground in their own battle for a top-four spot.

United have lost only one league game at home this season but Guardiola, whose side have won on their last two visits to Old Trafford, was confident albeit wary of Ole Gunnar Solskjaer's team that are hurting after a 4-0 loss at Everton.

"Four games left and we have to win our four games to retain the title," Guardiola told reporters on Tuesday.

"It's not an easy place to go but at the same time, it's a nice place to go.

"It is not as scary to go there and play when before it was maybe more difficult. We know exactly what we have to do. It's true we did better than United in the past three seasons.

"The fact they lost at Everton maybe means they are extra motivated. It's a different game when we play them, it's a derby."

City will be without influential midfielder Kevin De Bruyne after he suffered a hamstring injury in the 1-0 win over Tottenham Hotspur over the weekend.

The Belgian has already missed many games this season with knee and thigh injuries.

When asked if De Bruyne would be available for the derby, Guardiola said: "I don't think so. It is a muscular problem.

"We will see the next days, how he is getting better. But for tomorrow he is not available.

"We will see if he can play one or two more games and next season take care of him. We are going to speak with him, with the doctors and physios to make sure he is safe and fit."

Guardiola also addressed speculation around Riyad Mahrez who was reported by British media to be unhappy with his playing time at the club.

The Algerian winger has started only 13 of City's 34 league games this season.

"Riyad Mahrez will be with us next season and the next one and the next one," Guardiola said.

"I don't need to speak with him, we're delighted with his behaviour and the way he has played.

"He knows, and everybody knows, there is competition in the squad but Riyad is not going to move, he is going to stay here. He's happy and we're happy."

Australian Associated Press