Michael Carrick has warned that Manchester United cannot "afford a slow start" to the season, which starts when the Premier League champions begin their title defence on 17 August at Swansea City.

With José Mourinho returning to Chelsea and Manuel Pellegrini replacing Roberto Mancini at Manchester City, both of United's main rivals will be reinvigorated.

Speaking in Sydney, where United have begun a seven-day training camp as part of their pre-season tour, Carrick said: "This week, it's important because then we go on to quite a bit of flying after that – it's huge the start of the season we have. It's important we're ready for that, we can't afford a slow start this year, so these few weeks are vital for us."

United lost their opening tour game 1-0 to the Singha All Star XI in Bangkok at the weekend and play the A-League All Stars on Saturday at the ANZ Stadium. By then David Moyes will have had his most intense spell with his new squad since taking over, with the players having undergone a full training session on Monday.

Moyes was very much in the middle of the session, an approach that differs to his predecessor, Sir Alex Ferguson.

"The tour has been really good so far and there is a great atmosphere around the place," Carrick said.

"The manager has brought that in. He's enthusiastic and energetic and intense with his work, and that's rubbed off on everyone. Training has been good and there is a huge focus and a good feel around the place. I'm looking forward to this week especially, it's a big week really [for] training, because without the flying this week we've got a bit of time to prepare and get the work in.

"The actual training itself, there's only so many things you can do, and variations of playing football in that respect. The manager is hands-on in training. He's a lot different to Sir Alex in that sense – he tended to take a step back and let the coaches deal with it, whereas David Moyes tends to be right in the thick of it, which is good. It creates an intensity and everyone has responded to that."

Carrick added that the players and Moyes are still becoming familiar with each other.

"It's different for sure," he said, "because there's different people to answer to, different instructions coming in, the coaches and the manager have different views on different things, so it is something we are getting used to. I'm sure he's the same getting to know us, as time goes on we'll all improve together."

After Sydney, United have further stops in Japan and Hong Kong.