Hakim Ziyech cancelled out Raheem Sterling’s opener, before the Spanish full-back netted to seal the victory against a side they will meet again in the Champions League final on May 29.
It has been a difficult season for Alonso, with his Chelsea career looking to be on the ropes under the helm of previous manager Frank Lampard.
Marcos Alonso netted a late winner for Chelsea against Manchester City on Saturday
The Spaniard said he felt ‘very emotional’ after scoring the goal in what has been a ‘tough’ year
Since the appointment of Thomas Tuchel, Alonso has got himself back into the team on a rotation basis with last summer’s new signing Ben Chilwell.
After the game, Alonso told Chelsea’s official website that it was an emotional moment for him to score the winner.
He said: ‘I’m very happy, especially because it’s been a tough season.
‘I do my best every time I play to put pressure on the manager and try to play more. That’s what I want and I think every time I play I’ve done well so that’s what I need to keep doing.
‘With the goal, it was very emotional and I’m very happy for that.’
Alonso was exiled from Lampard’s squad following the £50m signing of Chilwell from Leicester.
Alonso had been exiled from the Chelsea squad under the helm of ex-boss Frank Lampard
Alonso though has worked his way back into the fold since Thomas Tuchel was appointed
He failed to make the matchday squad in 16 successive Premier League games, and it looked like his time at Stamford Bridge was coming to an end.
Since Tuchel has come in he has started eight league games out of a possible 16.
Alonso who has scored twice since coming back into the team, is hoping to end the season on a high and prove that he should start against Manchester City in the Champions League final.
He joined Chelsea from Fiorentina in the summer of 2016 and has played 165 times for the club in all competitions, scoring 24 goals.