Alastair Cook admits Younus Khan's unbeaten century has moved Pakistan closer to a series whitewash over England on the second day of the third Test in Dubai.

Khan scored the first century of the series to end the day on 115 not out, alongside Azhar Ali (75 not out),.as Pakistan took control and finished 222 for two at the close, 180 runs ahead of England.

"It was a tough day," Cook said, "That partnership has really taken the game away from us.

"When they came in they were still behind us. The pitch has obviously changed from yesterday but they played well. I think it's got slower and it made it a hard day for us."

The first day saw 16 wickets fall leaving England marginally in front of the 'hosts' on 104 for six overnight after Pakistan were bowled out for just 99.

However, England lost their remaining wickets quickly to total 141 in their first innings, before Khan and Ali produced solid performances to put Pakistan into a commanding lead after Monty Panesar and James Anderson made early breakthroughs.

Anderson removed Taufeeq Umar for just six before Panesar trapped Mohammad Hafeez leg before wicket for 21 to leave Pakistan reeling on 28 for two, before Khan and Ali came to the crease.

"Yesterday was a strange day with so many wickets to fall but it's disappointing to be on the end of it," Cook said.

"[Khan] played a fantastic innings there. He took the attack to the bowlers and didn't let them settle. We tried a lot of things to try and knock him out of that rhythm but he played really well.

"Obviously we want to keep their score as low as possible. The new ball is coming tomorrow so we'll try to grab an early one tomorrow and break the partnership as soon as we can.

"There's enough quality in our dressing room and there's some quality guys who can stand up. These guys have shown that once you get in it gets easier."