Chelsea's failure to qualify for Europe will help them become "a real threat" in the Premier League next season, says former Manchester United and England striker Wayne Rooney.

A 2-1 defeat at Sunderland on Sunday brought down the curtain on a disappointing season for the Blues, who have sacked Enzo Maresca and Liam Rosenior along the way.

While they began the campaign fresh from being crowned Club World Cup winners in July, the result on Wearside allowed the Black Cats to claim the final Europa League spot at Chelsea's expense.

Chelsea, who started the day above Sunderland in eighth, slipped to 10th, to also finish a point and two spots behind Brighton, who qualified for the Conference League.

It is only the third time since 1995-96 that Chelsea have ended a top-flight season in 10th place or lower.

However, they notably recovered to win the title in 2016-17 having been in exactly the same position at the conclusion of the previous season.

With Xabi Alonso taking the reins in July as their new manager, Rooney believes Chelsea will become a major force.

"I think they'll be a real threat next season," Rooney said on the Wayne Rooney Podcast.

"Obviously having one game a week, and then with Alonso coming in, I think it's exciting for the Premier League because I think he's got the potential to be a top manager.

"It gives him a period of time to feel his way into the club and get his ideas across. So I think it will benefit the football club."

Rooney's old club Manchester United had no European commitments this season and finished the campaign strongly to take third place in the Premier League.

Chelsea advanced through the league phase of the Champions League this term before suffering their joint-heaviest defeat in a two‑leg European tie, losing 8-2 on aggregate at the hands of holders Paris St-Germain in the last 16.

Rooney stressed that a less congested fixture list will only serve to benefit the Blues, who will have the advantage of more time on the grass together.

"Pre-season this year for all the managers at all the top clubs will be disrupted, obviously, because of the World Cup," Rooney added.

"I think that's where it will benefit Alonso, because he'll have that time once the season starts to get his ideas across. The teams in Europe might struggle a little bit. It could be an extra three days a week [on the training pitch]."