Thibaut Courtois says Chelsea's players never doubted Diego Costa's commitment to the club and feels claims he had a training ground bust-up were "not nice".

Reports suggested Costa had an argument with manager Antonio Conte and a fitness coach after receiving a massive offer from Chinese Super League Club Tianjin Quanjian prior to last week's Premier League match against Leicester City.

The Spain striker was omitted from Chelsea's squad for the 3-0 away victory, but Conte said it was due to a back injury and this week the manager revealed Costa was available to face Hull City at Stamford Bridge on Sunday.

Goalkeeper Courtois - who also played with Costa at Atletico Madrid - did not like hearing talk of unrest at training, and spoke glowingly of the Spain international.

"He has trained very well this week," Courtois said to Sky Sports. "Obviously it was not a nice rumour that went around that he had a fight or anything. 

"He had an injury and couldn't train. Obviously if you are not 100 per cent fit and you feel you cannot play it's logic that you don't train with the team.

"He looks very committed, we cannot doubt that about Diego. You can see that in all games he plays.

"Nobody in this team doubted it, so when the day before the game against Leicester that came out it was a bit of a surprise to the players, but it didn't affect us in any way because we know what the truth is. The rest is maybe just trying to destabilise Chelsea, but we don't let it."

Courtois opted not to ask Costa for his version of events as he had no doubt over the veracity of his injury.

"He was injured, so you don't need to speak with someone," added the Belgium international.

"You just ask, 'Are you OK?' and, 'Can you play on Saturday?' He said, 'No, I feel pain' and then you let it go because you know he won't play.

"After the win we had two days off and he trained here. Then he trained with us so I think everything is OK.

"We showed against Leicester that we are still the team that won 13 times in a row. Hopefully we can continue on the same run."