Neill went down in the box under pressure from Mikael Silvestre, bringing penalty appeals from the visitors’ bench.

Rennie waved away the claims and instead handed out Neill’s fifth booking of the season, which will rule him out of the second leg at Ewood Park on January 22.

“I thought it was a penalty but I would,” said Souness. “What bothered me most was the booking because whatever the incident was, it wasn’t a dive.

“We will ask Uriah to look at the incident again because it would be unfair for Lucas to miss the semi-final for that.”

Souness was delighted with the performance of his side, who responded almost immediately to Paul Scholes’ opening strike just before the hour when David Thompson nodded home Keith Gillespie’s right-wing cross just three minutes later.

It was not quite enough to force Blackburn’s first Old Trafford win since 1962 but it leaves the holders in a decent position ahead of the return leg, even if the result did come at a price, with both Thompson and David Dunn leaving the action early.

“Dunn had a reaction to an old calf injury which is a bit bewildering because he came back after three weeks out and played the full 90 minutes at Aston Villa on Saturday, then felt it again within five minutes tonight,” said Souness.

“He has to be a doubt for Sunderland on Saturday,” added the Rovers chief, who also lost Thompson with a twisted ankle.

For United, a difficult evening ended in total frustration when James McEveley got back to clear Ole Gunnar Solskjaer’s last-gasp effort off the line with his chest.

Ruud van Nistelrooy felt the young defender had used an arm and berated Rennie as he left the pitch, even though television replays showed the clearance to be perfectly executed.

“It was a great block from the defender,” admitted Sir Alex Ferguson.

“I actually thought it had hit the post. It means we have to go to Ewood Park and win but we are capable of that.”

Ferguson agreed with Souness that Neill’s booking had been harsh, although he added: “Blackburn had the majority of decisions, so I don’t think they can complain too much.

“I would also like to see the goal again because it looked like a sloppy one to concede, which is disappointing because the defenders had been doing well up to that point.”

Ferguson’s side could not win the game, even though he played his strongest League Cup line-up since winning the competition in 1994.

Skipper Roy Keane was the major absentee, with the United boss confirming his skipper had returned to training today after his recent hamstring injury and should be fit for Saturday’s trip to West Brom.

And despite playing the game in front of the largest crowd in Worthington Cup history outside of a final, Ferguson felt his side were not helped by a muted semi-final atmosphere.

“It was a funny atmosphere,” he admitted. “It lacked the great passion that you normally associate with semi-finals here over the years and it never really got going for me.”