Marko Marin fired Chelsea ahead shortly after half-time but a run of three wins came to an end as two mistakes were punished in a game the Blues had otherwise controlled.

Most of the action on a bitterly cold night in Leigh, Lancashire, came in the second half. Chelsea hit woodwork either side of Blackburn's goals which came in quick succession and were two well-taken strikes.

Marin, whose goal was also one to admire, played for an hour.

Team news
The defence and goalkeeper were unchanged from the win over Sunderland in the previous game. With Ruben Loftus-Cheek away with England Under-17s, Lewis Baker came into midfield with schoolboy Jeremie Boga handed the 'no. 10' role.

Milan Lalkovic moved from the wing to centre-forward with Marin starting on the left flank.

First half
Marin, fresh from his maiden first-team goal for Chelsea at the weekend was at the centre of the first incident of this game. A tug on him resulted in a free-kick wide on the left which the German took. It initially looked as if he had fired it far too high but the ball dipped quickly and bounced off the top of the crossbar. The back-peddling goalkeeper may well have made up enough ground to have it covered.

Sandomierski then had his hands warmed on a freezing night by a cross-cum-shot from Adam Nditi after Marin had played the ball quickly on to the overlapping left-back.

Alex Kiwomya on the other flank showed good early signs that his pace could take him beyond players out there, and he came infield on 22 minutes and exchanged passes with Boga but drilled a shot wide.

Blackman made his first save shortly after, down at his near post, and Chelsea launched a counter-attack when the resulting corner was cleared. Marin spotted a gap and played a pass behind the defence for Boga to run onto. Unfortunately the bounce of the ball made the shot more difficult than it might have been and the 16-year-old couldn't keep his effort down.

Chelsea were on top but needed to make more of our possession in the Blackburn half. Lalkovic was well-policed in the first period.

Blackburn hadn't really threatened but they nearly took the lead just past the half hour when Jamie MacLaren took his chance with a lob and Blackman retreated fast enough to tip over at full-stretch. The tall Chelsea keeper then made a good save from Kellen Daly's header at the corner.

The minutes leading up to half-time saw Chelsea turn up the pressure on Rovers.

Boga curled a well-struck shot but it never looked likely to beat the keeper and then Baker fired across the face of goal from a tight angle after Marin had found his run from midfield.

Nditi was denied for a second time in the match by Sandomierski. This time the defender controlled a high ball and excelled in striking on-target from a wide position. The keeper saved at full-stretch, as he did soon after from Alex Davey's header when found by a Baker free-kick.

Second half
Dermot Drummy made one change at half-time - bringing Nathan Ake on in midfield in place of George Saville.

Marin was also substituted a quarter of an hour into the half but not before he had put the Blues ahead with a quality goal. Collecting the ball midway inside the Blackburn half, he ran at the defence and sidestepped inside before dispatching a shot from the edge of the area into the far bottom corner of the net. It was pinpoint accuracy.

Chelsea could have had a penalty for a challenge on Reece Mitchell, who came on for Marin, had the referee not blown a second earlier for an offence in midfield on Ake. Baker came within a whisker of doubling the lead from the free-kick 30 yards out, rapping the crossbar with his strike. The Blues were soon cursing that misfortune when Rovers equalised two minutes later.

Losing the ball deep in the Blackburn half, they were caught on the break by a long pass to centre-forward Anton Forrester who was allowed to run behind the backline and beat the stranded Blackman. We were two-thirds of the way through the game and Forrester made it 2-1 to the home team with his second goal five minutes later.

Central defender Davey gave the ball away and couldn't catch Forrester who fired an unstoppable shot into the net.

Chelsea hit woodwork for the second time in the half when Boga's shot from just inside the area cannoned back off the post and there were appeals for a penalty for a challenge on Nditi. Andreas Christensen then had a header saved but there was no way back for the Blues.

Blackburn could have wrapped it up but Blackman saved well with his legs from MacLaren. The home side's two goals proved to be sufficient for the three points.

Under-21 manager Dermot Drummy said: 'It was disappointing because it was a game we shouldn't have lost.

'We made individual errors but regardless of the fact we have young players, the mentality in the second half was that we didn't really fight as a team. We were individuals off the ball and I have told them I was not pleased with that.

'We had control of the game on the ball but didn't have enough in the final third. It was three points thrown away and they have to understand that. We will hopefully learn from this and we will see who has a stronger mentality in the next game.

'The substitutions were planned. We knew that Marko Marin would play 60 minutes for first-team requirements and George Saville and Nathan Ake are travelling to Prague and we were asked that they did 45 minutes.'

Chelsea Jamal Blackman; Tika Musonda, Alex Davey, Andreas Christensen, Adam Nditi; Lewis Baker, Jeremie Boga, George Saville (c) (Nathan Ake h-t), Alex Kiwomya (Connor Hunte 60), Milan Lalkovic, Marko Marin (Reece Mitchell 60).
Unused subs Mitchell Beeney, Dion Conroy.

Blackburn Grzegorz Sandomierski; Peter Wylie, Ryan Edwards (c), Kellen Daly, Will Beesley; Darragh Lenihan (Hugo Fernandez Molina 63), Robbie Cotton; Tim Payne (Daniel Laverty 87), John O'Sullivan, Jamie Maclaren (Deniz Pero 90+2); Anton Forrester.
Unused subs, Matthew Unwin, Reece Hands.