Richard Rios' costly blunder in the first half at Stamford Bridge ruined Mourinho's hopes of a win over the club he is most closely associated with.

Mourinho and then-owner Roman Abramovich transformed Chelsea into a superpower after his appointment in 2004, winning three Premier League titles among seven major trophies across his two spells in charge.

The 62-year-old's managerial star may be on the wane following a decade without a league title, but his west London home-coming was still a box office occasion.

Mourinho had started the season in charge of Fenerbahce, who sacked him in August before he returned to his former club Benfica this month.

While Stamford Bridge is the scene of Mourinho's former glories, it has not been a happy hunting ground for him since.

He has failed to win any of his seven visits with Manchester United, Tottenham and now Benfica since leaving Chelsea for the second time in 2015, while his lone success in the away dugout came with Inter Milan in 2010.

Despite the loss, Mourinho took heart from Benfica's battling display.

"A defeat is always a defeat but this one can be a start for us. It was a stable performance," Mourinho said.

"When a team changes coach mid-season it's because things are not good. So we've had some difficulties. But we could have come away from here with a draw."

Having claimed he was "always a Blue" and still the "biggest" manager in the club's history on Monday, Mourinho, who retains a house near Stamford Bridge, had insisted Chelsea's fans would give him a warm welcome on his latest return.

The prediction proved spot-on as Mourinho's name was loudly chanted several times throughout the match by Chelsea fans who rose in unison to applaud him.

The Mourinho love-in inspired a strong start from Benfica, with Vangelis Pavlidis forcing Robert Sanchez to save at the climax of a flowing move.

Sanchez made another important stop when Dodi Lukebakio's drive was pushed onto the near post by the Chelsea goalkeeper.

- Mourinho frustration -

Mourinho's game-plan was exposing holes in Chelsea's defence and Heorhiy Sudakov should have done better with a chance that Sanchez gratefully smothered.

But Chelsea rode their luck to take an 18th-minute lead thanks to Rios' error.

Pedro Neto found Alejandro Garnacho inside the Benfica area and the Argentinian's cross triggered a panicked clearance from Rios, who diverted the ball high into his own net from close range.

Mourinho's luck was out, but he was still willing to play peacemaker when Benfica fans threw missiles at Chelsea captain Enzo Fernandez, who had a brief spell at the Portuguese club, marching down the touchline and gesturing to the supporters to stop the barrage.

Mourinho got his wish but Chelsea weren't so compliant and Tyrique George should have doubled their lead on the stroke of half-time when the young forward shot wide from a good position.

Benfica played with purpose after the interval but lacked the cutting edge required to carve out an equaliser.

Even a red card for Chelsea forward Joao Pedro for a high boot on Leandro Barreiro in the final seconds couldn't spare Mourinho from a frustrating defeat.

While Mourinho was left to bemoan the first loss of his Benfica reign, it was a welcome success for Chelsea manager Enzo Maresca.

Chelsea had lost three of their previous four games against Bayern Munich, Manchester United and Brighton, raising questions about Maresca's ability to take the club to the next level.

Maresca has led Chelsea to UEFA Conference League and Club World Cup glory since taking charge last year, but Mourinho waspishly diminished both those achievements this week.

The Blues' fourth win in nine games in all competitions this season was a timely response from Maresca.