Pep Guardiola says Manchester City will face the "best" Manchester United team of the season in Sunday's derby as they prepare to go head-to-head for the fourth time this season.

The 3-0 win over Derby in the FA Cup on Thursday made it nine matches unbeaten across all competitions and 22 goals scored for United, although City are also in top form after five straight wins.

City boss Guardiola said Ole Gunnar Solskjaer was having a positive influence on his team.

"From what I've seen in videos of their games, the players follow him (Solskjaer)," he told his pre-match press conference on Friday.

"I saw the commitment they had and it's getting better. Now it is their best moment of the season."

United's upturn has coincided with the arrival of Bruno Fernandes for an initial £47 million ($61 million) from Sporting Lisbon.

The Portugal international has made and scored goals and he has had a galvanising effect at the club.

"Sometimes the big players can make a good influence," said Guardiola. "He is an exceptional player and that is why Man United bought him."

Away wins

All three derbies so far this season have been won by the away side, with United twice victorious at the Etihad and City winning 3-1 at Old Trafford in the first leg of the League Cup semi-final.

But Guardiola has won all three of his league derbies at Old Trafford.

United were described by Liverpool manager Jurgen Klopp as defensive earlier in the season but that is not a view shared by the City boss.

"It doesn't look like that from what I have seen," he said. "I watched their recent games and they were incredibly aggressive and that will happen at Old Trafford.

"In some games they defended but I watched them at Goodison and they played a good game (the 1-1 draw at Everton last Sunday)."

The title has effectively gone for City, with Liverpool needing just four wins to wrap up the Premier League, while United, in fifth place, are embroiled in a battle for a Champions League spot.

Second-placed City are 15 points ahead of their cross-city rivals but Guardiola is not buying the theory that Sunday's meeting matters more to United.

"When we believe it's more important for them, we are going to lose," he said.

"We have to have belief, that is so important. I've never played a game thinking about points or whether it is more or less comfortable. Every game we play, we try to win."

Guardiola is hopeful that Kevin De Bruyne will be available to play at Old Trafford.

The Belgian injured his back in the League Cup final win over Aston Villa last week and did not feature in the FA Cup win at Sheffield Wednesday on Wednesday. (AFP)