"We have a lot of quality players in this side and they have to do more," said the former Feyenoord man. "Fernando and Stevie both have a chance to be footballer of the year, they've done really good things this year for Liverpool.
"But when you play for Liverpool you know you're under pressure and they have shown they can come up with the goals even when they're under pressure. That's what we all need to do."
The Dutchman is without a goal in the league since the 3-0 win over Newcastle on November 24th. "I'm struggling a bit at the moment," he admitted. "But I feel confident and I feel things are coming back.
"It's just a matter of time, I hope. I've got a good feeling that we can do great things for the rest of the season. We have the quality and we have to show it but at Middlesbrough we didn't do it once again. It's definitely two points lost," he remarked of Saturday's draw.
"Liverpool have more quality than Middlesbrough. It's up to us to show it on the pitch, but we didn't show it in the first half. The second half was better and we could even have won it, but it would have been too much for this game."