Manchester United felt the force of Morten Gamst Pedersen once again as Blackburn set up a tantalising Carling Cup semi-final decider at Old Trafford in a fortnight.

Rovers' two-goal hero in their Old Trafford triumph four months ago, Pedersen provided United with another nasty shock, blasting home an equaliser to Louis Saha's opener which ensures the second leg will start level.

After a pulsating contest, Sir Alex Ferguson's men will regard themselves favourites to face Wigan or Arsenal at the Millennium Stadium on February 28.

But Rovers are in such good form just now - and have such a fine recent record against United - no-one at Ewood Park will be giving up the fight.

Twenty-four hours after a first semi-final which needed a floodlight failure to spark it into life, the electricity was tingling in this north-west derby from the very start.

Blackburn, unbeaten in their last four outings against United, should have been ahead inside the opening 23 seconds.

David Bentley was the provider, picking out Robbie Savage on the penalty spot with a superb cross. The Welshman let fly with a vicious volley but Edwin van der Sar, already diving, kept it out with his legs.

It launched what was to be a frenetic opening period, with the fact it yielded only two goals and left 22 players still taking part in the contest a surprise.

Darren Fletcher was fortunate when Craig Bellamy was too flat-footed to react when he failed to cut out Pedersen's cross, then Bentley delivered a ball from the other flank that Rio Ferdinand was at full stretch to stop Bellamy from reaching.

When Bellamy also lofted a volley over, the suspicion started to mount among Blackburn's biggest crowd of the season - twice the number that turned out at Wigan 24 hours earlier - that their side would pay for their failure to seize the initiative. Those fears were totally justified.

Saha was surprisingly preferred to Ruud van Nistelrooy in a strong United line-up that defied Sir Alex Ferguson's pre-match assertion Saturday's Manchester derby at Eastlands is a far more important affair in the Red Devils' calendar.

Yet the injury-prone Frenchman has shown a liking for this competition already this season with three goals, including a double in the last round at Birmingham.

So, when Ryan Giggs slipped a pass through the Blackburn defence, Saha latched onto it with relish, sped into the area, then beat Brad Friedel with a clinical low finish.

Decisive victors on the same ground at the same stage of the competition three years ago, United would have hoped to use the opener as the platform for another comprehensive triumph.

Instead, this obdurate Blackburn side summoned the defiance their manager would have showed when presented with a similar situation and fought their way back into the tie.

If Saha licks his lips when the Carling Cup is mentioned, Pedersen loves the taste of United's defence.

The Norwegian midfielder has been in decent scoring form lately and when Shefki Kuqi flicked on Ryan Nelsen's long ball, Pedersen wasted no time in thundering a shot into the corner - to the delight of the home supporters in the 24,348 crowd.

Kuqi's main involvement prior to that had been a barge into van der Sar which brought one of a regular stream of protests from the home camp at the decisions of referee Rob Styles.

Bellamy, never one to hold back an opinion, offered Styles a few choice words. The official responded with a yellow card, instantly wiping away the Welshman's hoped-for visit to old club Newcastle on January 21.

That spat was minor compared to the one which erupted just before the break as Wayne Rooney found himself tangled up in Savage's legs.

Alan Smith's attempt to resolve the impasse was a wild lunge at the Welshman, which could easily have resulted in a red, rather than yellow card.

Savage, now on the ground, twisted away and wrapped an arm round Rooney's throat, the England firebrand responding with a clear shove in the Blackburn man's face. All three were cautioned, much to Hughes' obvious disgust, Rooney's punishment ruling him out of next week's FA Cup replay with Burton.

The fire, and some of the pace, went out of the contest after half-time. It was hardly surprising, although there was still enough competitive spirit for Tugay and Saha to find themselves in Styles' notebook.

Kuqi blasted a good chance into the side-netting and Rooney saw his goalbound drive crunch into Saha's back as the search for a winner continued.

The last opportunity fell to Lucas Neill, but the Australian full-back blazed over, so neither side can start planning their trip to Cardiff just yet.

Teams

Blackburn Friedel, Neill, Todd, Nelsen, Gray, Bentley (Emerton 76), Savage, Tugay (Reid 76), Pedersen, Kuqi (Dickov 84), Bellamy.

Subs Not Used: Enckelman, Khizanishvili.

Booked: Bellamy, Savage, Tugay, Dickov.

Goals: Pedersen 35.

Man Utd Van der Sar, Neville, Ferdinand, Brown, Silvestre, Ronaldo, Fletcher (O'Shea 85), Smith, Giggs, Rooney, Saha (van Nistelrooy 82).

Subs Not Used: Howard, Bardsley, Rossi.

Booked: Smith, Rooney, Saha, O'Shea.

Goals: Saha 30.

Att: 24,348

Ref: R Styles (Hampshire).