Willian said defending champions Chelsea will continue to battle for the Premier League title after moving 11 points behind leaders Manchester City by beating Huddersfield Town.
The Brazilian was instrumental in Tuesday's 3-1 away win, producing a goal and two assists as Chelsea bounced back from Saturday's shock 1-0 loss at West Ham.
Although Chelsea's results have been inconsistent, while City have won 14 successive league games to establish a dominant cushion, Willian believes the Blues will continue to push hard to defend their crown.
"I think we had a great game, we had possession and tried to play the ball," Willian told BT Sport. "We created a lot of chances and we have to carry on.
"Always when I play I want to play well and make a difference. Of course I want to play every game, but only 11 can start.
"We know it’s difficult [to win the title], but we have to fight until the end. We are Chelsea, we are a big club –we have to fight."
Eden Hazard accepted it was necessary for Chelsea to show a reaction after going down 1-0 at the London Stadium last time out.
"We had a bad game against West Ham – when things like this happen we need to bounce back," Hazard told BT Sport.
"We did well today, the fans are happy, we are happy – let’s move forward for the game against Southampton. We’ll be ready and will fight to the end.
"When we play like this it is easy to play – good movement, the manager wanted us to move a lot and not always stay in the same position.
"We have a lot of games in a short period of time, but since I came to Chelsea it’s always been the same."
