Manchester - Manchester United manager Louis van Gaal refused to look too far ahead in the Premier League title race despite seeing his side go top after comfortably beating Sunderland 3-0.
Manchester City's 4-1 defeat at Tottenham Hotspur earlier on Saturday enabled United to take top spot for the first time since Van Gaal took charge at the start of last season.
But the Dutchman believes it is too early to gauge United's chances of a first title since legendary former manager Alex Ferguson delivered his 13th and final championship in 2013.
"Ask me that question again in May," Van Gaal said to reporters after goals from Memphis Depay, Wayne Rooney and Juan Mata at Old Trafford left Sunderland still looking for a first win of the season.
"To continue is very difficult in this league. Last year when we had 13 points from 10 or 11 matches, we had to chase and at the end of the season we finished fourth.
"This year is a big difference. You can start better from the top than the bottom, but it shall be very difficult. In May you can ask me the same question.
"We have to continue, although we shall lose also. We play away at Arsenal next week and they are one of the most difficult teams to beat, but we won there last season so it is possible.
"I think Manchester United can win against any team, but also you need luck and we had that today (Saturday) because it was the last minute of the first half."
United opened the scoring in the fourth minute of first-half injury time when a glorious Daley Blind pass allowed Mata to square for Depay to score his first league goal since signing from PSV Eindhoven.
Rooney then ended an 11-game goal drought in the Premier League as he bundled in his 171st league goal for the club, drawing him level with Denis Law in third place in United's all-time list.
"It doesn't matter who is scoring goals or making goals. I am not interested, although personally for Rooney, Depay and (Anthony) Martial it's very important," Van Gaal added.
"I am a happy coach because Rooney and Depay have scored in the Premier League now and that's fantastic for their confidence."
Sunderland remain bottom of the table without a victory after failing to improve on a record that has seen them win just once at Old Trafford since 1968.
That came in May 2014, just before Van Gaal's appointment at United, as they narrowly avoided relegation and manager Dick Advocaat knows his side needs to improve if they are to avoid that fate this time.
Sunderland have the worst defensive record in the division and although they produced a disciplined performance, they switched off when Patrick van Aanholt allowed Mata to get in behind him for Depay's opener.
And less than 60 seconds into the second half they conceded again to Rooney before Mata completed the scoring in the last minute.
"We can't keep saying we will take the good things out of the game," Advocaat said. "You can say we were well organised against a good team like United, but we gave the game away in two minutes.
"Against a team like United, at 2-0 down it's quite difficult to come back. I can accept losing sometimes, but we made it very easy for them in the second half.
"Do we have to change things in the squad? That's what we have to think about, but we don't have much opportunity."