ABU DHABI: England are aiming to score at least 500 in their first innings, a tired captain Alastair Cook said after his unbeaten 168 helped the tourists reduce Pakistan's lead in the third day of the first test on Thursday.

Pakistan, playing in the United Arab Emirates, are unbeaten in seven series in their adopted home, a run that includes a 3-0 whitewash against England in 2012.

The tourists looked set for more misery after Pakistan declared on 523-8 on Wednesday, but Cook then batted all day as he made a record-extending 28th England test century to help his side reach 290-3 by the close.

"It has been tough physically and I'm pleased to have got through that last hour and a half when I was a little bit tired," Cook told Sky Sports. "We have got to get ourselves up to 500."

Cook's latest ton moved him ahead of team mate Joe Root as test cricket's top scorer in 2015, with Root (3) now at the crease after Mark Wood's (4) cheap dismissal.

Cook struck his maiden test century in Nagpur, India, in 2006 and is arguably the world's best batsman on subcontinent pitches.

"I do feel as if I can score aggressively when I need to and defend well," added Cook. "When you've got men around the bat you can't just run down and whack the ball over the top."

Ian Bell, who shared a 165-run second wicket partnership with Cook, paid tribute to his captain's stamina.

"He has shown in this part of the world he can do that for days. He's ready to go again tomorrow," Bell told reporters.

"He's led from the front, his shot selection against the spin was world class."

Bell and Cook are two of four survivors from England's last series against Pakistan and both seem keen to make amends for that woeful showing.

Bell's knock of 63 was more than he made in six innings combined the last time they played in the UAE, the 33-year-old digging in to repel Pakistan's attack as he scored just one run from the first 33 balls he faced before becoming more expansive.

"It's difficult to start (in the) subcontinent, your first 40-50 balls are generally tough and if you can get through that it will get a little bit easier," added Bell.

"I'm happy with what I did today, but gutted I'm not there tomorrow to cash in and go bigger."