Michael Carrick believes this could be a defining week in Manchester United's season as they continue their assault on the treble.

United will start a crucial week by aiming to cement their position at the top of the Premier League with victory over Portsmouth at Old Trafford tomorrow night. They then travel to White Hart Lane three days later to take on Tottenham Hotspur for the second time in six days.

United will then switch their focus to Europe next Wednesday when they travel to France for the first leg of their last 16 Champions League tie with Lyons.

“Weeks like this can define a season. If we can get the three wins we are aiming for then we will be in good shape,” Carrick said.

He admits United are still smarting from last season’s FA Cup final defeat to Chelsea, and the former West Ham United midfielder is keen to go back to Wembley and erase that memory this year. However, they have to negotiate a tough hurdle in the fifth round with a match against title rivals Arsenal.

He said: “A club like ours is in competitions to win them and we're now starting to look towards Wembley. Of course, you do not want to get too carried away because there are tough games ahead.

"But we want to be there again come May, especially because we came so close last season and lost right at the death. We're determined to put things right this season."

United completed an unprecedented treble in 1999 and United manager Sir Alex Ferguson believes his side can repeat that success provided they can avoid the injuries that plagued last season’s campaign.

"The treble is achievable for us, there's no doubt about that,” he added. "Last season I'm certain that if we'd had a stronger squad we could and would have done it. But players like Gary Neville, Rio Ferdinand, Nemanja Vidic and Mikael Silvestre all got injured at a bad time.

"We didn't have an experienced central defensive pairing to go into the Champions League semi-final second leg against AC Milan, but we are stronger this time.

"We know it would be tremendously difficult for us, or any team, but if you are in the competitions then it is a possibility."

United continue to be without long term absentees Neville and Silvestre, but they were also without Vidic on Sunday, the centre back missing the FA Cup victory over Tottenham with a virus.

However, Ferguson believes United’s strength in depth, especially in defence, could make the difference this season.

"Like all managers I'm hoping to steer clear of any injuries for these tough games that lie ahead,” he said. "If we get to the semi-final of the European Cup and the FA Cup and are still involved in the League this season then we must have some sort of a chance, it might not be a great one but it's some sort of chance."