Ronny Deila has urged Virgil van Dijk to stay with Celtic as the club competes on four fronts after the January transfer window.

Van Dijk scored twice in a 4-0 rout of 10-man Hearts at Tynecastle to help ease Celtic into this afternoon's Scottish Cup fifth round draw at Hampden.

Hearts coach Robbie Neilson was irritated that referee Willie Collum would not explain why he sent off Morgaro Gomis after only eight minutes, or why he gave a penalty in the second half when John Guidetti appeared to slip. But Deila purred about Van Dijk's goals and Celtic are currently top of the SPFL Premiership and will enter 2015 still in both domestic cups and in the last 32 of the Europa League.

"I will not be surprised if there is more interest in Virgil," said the Celtic manager about the Dutchman. "He is a fantastic football player and he is improving all of the time. Virgil works hard in training and he's more focused. He's going to be expensive, but he loves to be here. I really hope he can stay here and that we can keep him. That is the priority.

"If he is going, I hope it is to the biggest clubs and not an average Premier League team. He has everything you need to do it at a top-four club level. But I hope we can keep him to challenge for the four competitions and that would be good for him, too."

Gomis's red card helped Celtic towards an easy win. "I had been thinking a long time about this game and its importance," said Deila. "I'm really happy and relieved to know the goals are still in sight and I know we are now going to have a fantastic spring. It was a calmer afternoon that I expected beforehand. Of course, the sending off changed the game. We talked a lot before the game about the pitch not being so big and that we'd need to be together and aggressive as first defenders. We did that and Hearts almost didn't have the ball, especially after they went to 10 men. That discipline and team-spirit was very good."

Neilson was upset by both contentious decisions, especially the penalty given against Brad McKay, and Collum's refusal to discuss them. "I am more annoyed at that but I'm also more annoyed that you can't speak to them.

If somebody makes a mistake

I would rather they just came and said 'look, I did it' and we could move on.

"I thought the players worked but there were decisions I am very disappointed in. Everyone knows what the outcome

of them should have been but the one man who makes the decision didn't see it like everyone else. I'm not going

to let somebody's performance be a blight on our start to the season. As soon as we got the second decision against us the game was finished.

"We were in a game last week where two players [Rangers pair Kenny Miller and Kris Boyd] were booked for tackles that were far worse than Morgaro's. Morgaro goes in and wins the ball and the referee decides it's a sending-off. Morgaro's tackle, we can't really argue against it because they always have things they can say - it's reckless, or at pace - but for me the second one, the penalty, is the real changer in the game."

Asked if he thought Guidetti had been guilty of simulation, Neilson said: "The fact you

are asking me the question probably answers your own question. I'm not going

to try to get players sent off

or booked retrospectively."