FA Premiership/ Blackburn 0 Liverpool 1: The last time Djibril Cisse graced this stage he departed on a stretcher in agony, his left leg shattered and his career in serious doubt.

The Frenchman strutted from the field at the end yesterday flinging his shirt into the Darwen End with the locals spitting abuse in his direction and the home dugout simmering with resentment over his apparent non-involvement in this contest's key incident.

At least an acrimonious occasion punctured by spats between opposing players ended with some unity between the managers, Rafael Benitez and Mark Hughes both criticising the complicated offside rule that allowed Liverpool's winner to stand.

"There's too much open to interpretation, and no one knows where they are or what the rule is now," growled Hughes. The fact that his opposite number concurred suggested he had a point.

The game had been meandering when John Arne Riise's throw was chested on by Robbie Fowler beyond a trio of Blackburn players towards Cisse in an offside position. The Frenchman dangled a leg as if to gather possession but, realising he was alone beyond the last defender, withdrew his foot and failed to make contact. Fernando Morientes duly wriggled round the static Rovers players to collect and, with the defence appealing for offside, the Spaniard calmly pulled the ball back for Fowler to side-foot into the empty net.

The home players were apoplectic, a huddle taking their grievances to the linesman Barry Sygmuta. The FA's clarification of the ruling states that a player is interfering if he "plays or touches the ball passed or touched by a team-mate".

Even if Cisse changed his mind, he had clearly intended to play the ball.

"The linesman said that because Cisse didn't touch it, that makes him not interfering, but how does he know that from the position he was in?" said Hughes. "He was 60 yards away and anyway you can not touch the ball and still distract an opponent."

"They need to change the rule because they're creating problems for the referee," added Benitez. "If he's offside, he's offside. Finished. There wouldn't be a problem then."

In the meantime, he could celebrate a fourth goal in four starts for Fowler, a seventh successive win in all competitions and a welcome gift from Sygmuta to mark his 46th birthday.

Yet, for Cisse, this afternoon suggested he is at his most effective when not interfering with play. His reaction to an early foul by Robbie Savage, who was booked, had riled the home support though they had reverted from abuse to mockery by the end. Twice Cisse was put clear, first by Fowler and later by Harry Kewell, only for Brad Friedel and the woodwork to thwart him both times. The first chance was taken early, his shot cannoning through the goalkeeper's block to bounce down and loop on to the bar.

The second squirmed beyond Friedel's save only for Cisse, running behind the American, to belt against a post with the goal unguarded.

Cisse was also involved in a touchline altercation with Hughes before half-time, Blackburn's manager angered by the striker's reaction to an ugly Lucas Neill tackle. Rovers seemed incensed by Cisse's presence and only recovered their poise late on to force Liverpool into retreat.

But Jamie Carragher and Sami Hyypia were resolute and the hosts' only clear-cut chance came when Morten Gamst Pedersen and Craig Bellamy combined to eke out space for Savage but the midfielder volleyed into the side-netting. This was a 30th clean sheet of the season for Jose Reina, and the side's 33rd. They have conceded only three goals in seven matches, which bodes well for Saturday's FA Cup semi-final against Chelsea.

Steven Gerrard will be available, the midfielder being rested here with a tight hamstring, but Fowler is ineligible. However, his chances of earning a longer-term contract must have been improved. "If I say no, it'll be difficult for him but he'll understand," said Benitez. "If I say yes it'll be good for me, him and the supporters, but I need to analyse more things. I am not in a hurry but if he continues to score goals then it will be an easy decision. The more he scores, the more he's likely to stay."

Benitez added: "He is a very good professional. "It's not a problem whether or not he has a contract. He is working hard because he loves Liverpool."

• Guardian Service