Manchester United manager Jose Mourinho insists former club Chelsea should still be considered favourites for the Premier League title, despite the champions losing their opening game to Burnley.

Antonio Conte's men had Gary Cahill and Cesc Fabregas sent off as they went down 3-2 at Stamford Bridge, while the Italian is reportedly unhappy with his club's business over the transfer window.

In contrast, Mourinho appears to have conceded defeat in United's attempts to land a fourth signing of the window to add to Romelu Lukaku, Victor Lindelof and Nemanja Matic, with Ivan Perisic and Gareth Bale among those to have been linked with a switch to Old Trafford.

The Portuguese piled the pressure on his former employers by reasserting their status as Premier League title favourites as Conte prepares for Sunday's trip to Tottenham.

"For me the favourite is the champion, always," Mourinho told reporters ahead of Saturday's trip to Swansea City.

"It doesn't mean you are going to win it, I think it is the stamp that you have when you are champions, it is that the next season you are the favourite."

United's purchase of Matic from Chelsea reportedly upset Conte, but Mourinho insisted his side's title rivals cannot complain about their transfer business before the window closes on August 31.

"If they have problems, the problems are going to finish in a couple of weeks because in a couple of weeks the market is closed and they don't have problems any more," Mourinho said.

"If they have, and I don't know if they have but if they have, in a couple of weeks the problems are over. They have very good teams, very good players and I don't see any reason for them not to be fighting for the title.

"When people say, for example, Chelsea lost an important midfield player [Matic], if you lose one but you buy [Tiemoue] Bakayoko and [Danny] Drinkwater for example, what's the problem? The problem is when you sell and you don't buy.

"When you sell and you keep buying, what's the problem? You are probably even stronger, so I think every top team in the Premier League is strong enough, is potentially strong enough with the financial situation to be fighting for everything and, when everybody is also in Europe, five in the Champions League and two in the Europa League, you have the top seven teams playing for everything and all of them are strong."