Jose Mourinho is uncertain about Chelsea's chances to clinch the title next season citing the many improvements made by his team's rivals during the summer transfer window.

After lacking from a regular scorer last season, Chelsea are close to finally completing the signing of Diego Costa while Mourinho expects Cesc Fabregas to lead the midfield alongside Nemanja Matic.

Nevertheless, Manchester City, Liverpool, Arsenal and Manchester United are also expected to bolster their squad with a busy summer transfer window.

Mourinho promises Chelsea will make progress but is uncertain about if it will be enough to claim any titles after a season without silverware.

"Next season will be very, very difficult, even more so. I know Chelsea will be better, but maybe the other teams will be better too, so it will again be the kind of league where you don't know if you're going to finish first or finish sixth. In this moment I have to think and feel and say we want to finish first," Mourinho was quoted by Chelsea official website.

"I enjoy this club, I like the club, and I like the league. I love the way people live football in this country. I was a little part of the process that made Chelsea a force in the last decade, and I come back with the dream to try to be a little part again of the next decade.

"After 10 years of titles and great moments, this is a moment to rebuild again, because teams don't last for ever. Clubs yes, but not the teams. In the same club you have to build another team. That's what we are doing, and for sure the results will come."

Meanwhile, Mourinho heaped praised on Eden Hazard and expects him to keep growing next season.

"Obviously the fans enjoy and respect people like Gary Cahill, Cesar Azpilicueta, John Terry -- people that are so stable during the season and do an incredible job for the team -- but people like Eden bring the magic and winning matches in one action. They have the flair and the artist's touch of the football," he added.

"At the same time, he was not just that. He had a big evolution and he scored more goals than before. His work-rate for the team improved a lot too, so for a player like him he deserved it and the fact he was recognised by the fans gives him more appetite for the next season to be even better."