Nottingham Forest boss Steve Cooper felt his side could have been more “ruthless and aggressive” in the 4-1 victory over Blackburn in the Carabao Cup.

Wales international Brennan Johnson fired the visitors in front from the penalty spot, and the Reds could have had a few more but for goalkeeper Aynsley Pears making five saves in the first period.

Scott Wharton’s glancing header brought Blackburn level at the break, but Forest turned on the style in the second half.

Jesse Lingard put the away side back in front with a deflected free-kick and Forest set up their first quarter-final in the competition since 1994 with two goals in the final 10 minutes courtesy of Taiwo Awoniyi and Johnson again.

Cooper said: “I thought we could have been a bit more ruthless and aggressive with our play and because we weren’t quite at that, we allowed Blackburn to have some moments.

“We should have been out of sight after 15 or 20 minutes – eventually we got the first goal but I wanted the team to step on and take the game away from Blackburn.

“I never felt like we did not control the game but I did not like our decision making after the goal. We should never have been in that situation in the first place.”

Cooper hailed the performance of attacker Johnson, who scored two on his return from World Cup duty.

He said: “I thought Brennan was a right threat today, and thought it was only a matter of time before he created and scored again.

“I thought he was excellent tonight, he was the real threat in the game and he took the penalty really well, he committed to his technique and decision so he looked clinical.

“So job well done and a load of positives but also some bits that I didn’t quite like in that performance as well.”

Blackburn manager Jon Dahl Tomasson knew it was going to be a tough ask coming up against a Premier League side.

Championship Rovers made 11 changes to the side from their 2-0 victory over Norwich at the weekend but Tomasson insists his younger players will learn from the experience.

He said: “We knew it was going to be a challenge playing a Premier League club who have invested a lot of money.

“This journey we have had in the cup has been good and has been one where we have played young players.

“For the young players, they will learn from playing a Premier League club. It’s difficult to find positive things but we are always looking at the development and also getting the balance right, and what is coming up in the upcoming period.”