Jose Mourinho has warned his Chelsea players that they "must improve" this coming season if they are to retain their Premier League title.

The Blues stormed to the top-flight crown last term after seeing off the challenge of Manchester City.

Chelsea have so far brought in two new faces this summer, with Radamel Falcao and Asmir Begovic being drafted in to replace outgoing players.

This is in stark contrast to title rivals Man City, Manchester United and potentially Liverpool, who have each splashed the cash in an attempt to close the gap on the champions.

"The other clubs are going to improve immediately because of the top-quality players they bought," Mourinho told ESPN. "To improve, we have to improve ourselves.

"I have to be a better coach, they have to be better players, we have to have a better medical department. We must improve by ourselves."

Chelsea get their 2015-16 campaign underway on August 8 when they take on Swansea City at Stamford Bridge.