Crawley Town suffered an injury scare as they conceded a two-goal lead to lose 3-2 to a Chelsea XI at the Checkatrade.com Stadium.
Efforts from Josh Simpson and Izale McLeod put the Reds 2-0 ahead at half-time.
But the young Blues scored three goals in six minutes in the final quarter of the game to snatch victory in an entertaining game.
Of more concern to Reds manager John Gregory was Gavin Tomlin going off injured early in the second half.
Tomlin banged his fist on the turf as he went down in midfield and had to be helped off the pitch.
Crawley begin their League One campaign at Barnsley a week today.
McLeod spurned a great chance to put Crawley ahead inside three minutes when he was cleverly fed by strike partner Gavin Tomlin but his shot was saved by keeper Bradley Collins.
Patrick Bamford twice went close from 20 yards for Chelsea, the first being held by Brian Jensen and the second floating inches wide of the far post.
Chelsea enjoyed lots of possession in the first half but continually chose to shoot from distance while Crawley looked more incisive with their attacks.
Lewis Young hooked Gwion Edwards’ inviting cross wide of the far post on 24 minutes and Jimmy Smith fired narrowly past the near post just past the half-hour mark.
It was no great surprise when Crawley broke the deadlock on 34 minutes with a good left-footed finish from skipper Simpson after Dean Leacock nodded Ryan Dickson’s cross back across goal.
McLeod doubled the advantage a minute before the break when he got in behind the defence and fired cross Collins into the far corner.
The flow of the second half was disrupted by a succession of substitutes including a debut for Crawley’s Mitch Rose, who signed on loan from Rotherham on Thursday.
Trialists Anthony Stewart, Charles Banya, Austin Dias – a 21-year-old American midfielder – and Harold Odametey were also given game-time.
Bamford was inches away from halving the deficit with a delightfully curled 20-yard effort which came back off the inside of the far post with 18 minutes remaining.
Ola Aina made it 2-1 on 79 minutes with a flicked header into the far corner and within 60 seconds fellow substitute Charlie Colkett’s direct free-kick found its way through a crowd into the far corner for the equaliser.
Chelsea then grabbed a winner on 84 minutes when goalkeeper Raphael Spiegel fumbled Charly Musonda’s speculative 25-yard effort over the goalline.
Crawley were playing their second XI by the time Chelsea scored their first goal so Gregory will not be too concerned by the scoreline.
But he will hope Tomlin is not ruled out of the Barnsley game.
Crawley: Jensen (sub Spiegel 46); Oyebanjo (sub Bawling 62), Leacock (sub Bradley 60), Walsh (sub Stewart), Dickson (sub Odametey 78); Young (sub Dias 69), Simpson (sub Henderson 46), Smith (sub Rose 62), Edwards (sub Essam 69); Tomlin (sub Banya 53), McLeod (sub O’Connor 48). Subs not used: Richefond.
Chelsea: Collins, Kane (sub Aina 57), Brady, Davey (sub Harley 72), Dabo; Houghton (sub Colkett 46), McEachran (sub Mitchell 62); Perica (sub Kiwomya 46), Saville (sub Musonda 62), Palmer (sub Rodriguez 72); Bamford. Subs not used: Granger.
Referee: Darren Sheldrake.
Attendance: 1,349 (159 away).