Chelsea's hopes of a top-four Premier League finish took a hit as they could only claim a late draw at struggling Bournemouth on Saturday.
Alonso gave the hosts a half-time lead at the Vitality Stadium, only for Jefferson Lerma and Joshua King to strike twice in three minutes after the interval.
Spaniard Alonso rescued a share of the spoils with a header five minutes from time, leaving the Blues only four points ahead of Manchester United - who play on Sunday - in fourth.
Simon Collings was on the south coast to cast an eye over the performances of Frank Lampard's men...
Willy Caballero 7
Made good saves early on to keep Chelsea in it and then could do nothing to stop Bournemouth’s goals.
Cesar Azpilicueta 6
Performed the best of the players in Chelsea’s back three. Filled in at centre-back in a back four for the final 25 minutes, too.
Andreas Christensen 5
Was good in the first half but then struggled after the break. Out-jumped by Lerma for the equaliser. Booked later on.
Fikayo Tomori 5
Started slowly and, while he improved before half-time, got exposed in the second half as Bournemouth opened Chelsea up.
Reece James 6
Had good moments when going forward and it was his cross that provided Chelsea’s opening goal in the first half.
Jorginho 5
Didn’t run the game from midfield as he usually does. Booked and will now miss Chelsea’s next two League games.
Mateo Kovacic 7
Another solid display from a player who is consistently one of Chelsea’s best performers each week.
Marcos Alonso 8
Another two goals to add to his one against Tottenham last week. Got forward time and time again and looked bright.
Pedro 7
Handed a rare start and looked bright at times. Linked up well with Olivier Giroud and didn’t stop running all game.
Olivier Giroud 6
Worked hard up front to act as a focal point. Grabbed an assist when his audacious flick hit the crossbar and rebounded to Alonso.
Mason Mount 6
Had a few nice touches but was quiet overall. Struggling to recapture the form he enjoyed earlier in the season.
Subs
Willian (on ’64) 6
Provided his usual trickery and skill when he came on. A strong cameo appearance.
Ross Barkley (on ’64) 5
Neat and tidy when brought on, but failed to make the decisive impact needed.
Michy Batshuayi (on ’72): 6
Bright and lively when he came on. Found the back of the net but it was ruled out for offside.