Odion Ighalo scored twice as Manchester United ruined Wayne Rooney's reunion with his old club by beating Derby 3-0 on Thursday to reach the FA Cup quarter-finals.
Luke Shaw's opener and Ighalo's strikes helped set up a quarter-final tie at Norwich later this month.
It was a disappointing night for Derby player-coach Rooney, United's record goalscorer, who was twice denied by Sergio Romero.
But United extended their unbeaten run in all competitions to nine games ahead of Sunday's derby visit of Manchester City and remain in the hunt for the FA Cup, Europa League and a top-four finish in the Premier League.
Manager Ole Gunnar Solskjaer said: "Today was the highest priority because we're not going to pick and choose games or competitions. We have to go for everything, that's what it is to be at Manchester United.
"It's another away draw, we're use to that now. Is it a seventh in a row? We'll have to do it the hard way if want to go all the way. We've got a chance now.
"I'm very pleased with the performance and to go through. You never know, away from home, being the favourites and having City on Sunday how it'll affect their mindset, but it was professional.
"We've found form and defended well, we've had seven clean sheets in those nine games."
United are chasing a record-equalling 13th FA Cup triumph but survived two early scares when Louie Sibley shot wide and Romero saved Rooney's free-kick.
But the visitors took control at Pride Park after 33 minutes when Shaw scored just his second career goal, his volley bouncing over Kelle Roos.
Ighalo made it 2-0 seven minutes later when he held off Craig Forsyth and found the corner.
Martyn Waghorn went close for Derby after the break but Ighalo ended the contest when he fired home to complete his double with 20 minutes left.
Solskjaer said: "He's doing what he says on the tin and what we asked for when we signed him. I'm very happy with him. That type of striker is vital for a team.
"There's more to come. He'll improve and get sharper and more used to us. I've got no doubt he'll only get better."
The 30-year-old now has three goals from just two starts. "As long as my team-mates believe in me, the boss believes in me and the fans believe in me, I just have to keep going," Ighalo said.
"I don't care what anyone says. We want to keep the momentum going and make sure we do great this season."
Rooney almost grabbed a consolation but Romero produced an excellent stop to turn his late free-kick over. "Everyone loves Wayne, all the supporters at Manchester United appreciate what he did," said Solskjaer.
"He played well. He shows class and sometimes he has too much time on the ball for my liking."
Rams manager Phillip Cocu said: "If the first free-kick goes in, sometimes it defines a game. You have to be really effective and on that side they were much better than we were. I'm quite satisfied with the performance."
Derby are 13th in the Championship, eight points adrift of the play-offs with 10 games left and Cocu remained cautious over their chances.
He said: "Everyone talks about the play-offs but I really like to talk about the next game. Blackburn are above us in the league and we have to deliver a good performance in every game. Slowly we are heading in the right direction."
