Alastair Cook compiled 263 runs in the longest Test innings by an England player as the tourists finished day four of the first Test on 569 for eight against Pakistan.
The left-handed opener's remarkable powers of concentration lasted for 190 overs and four minutes shy of 14 hours - the third longest innings in the history of the game - to leave a draw the most likely outcome in Abu Dhabi with a day to play.
In an incredible display of mental resolve and physical determination, the 30-year-old hit 18 fours but dealt mainly in flicks and nudges all around the wicket as the tourists reached stumps with a lead of 46.
While a draw seems by far the most likely outcome, Cook - ably supported by half-centuries from Ian Bell yesterday and Joe Root and Ben Stokes today - has put England in a position where they could leave the hosts to bat out a tricky couple of sessions to save the game, albeit on a surface which has remained placid throughout.
Cook had been dropped on 147 last night, and received another reprieve early on Friday as he got an inside edge to the impressive Wahab Riaz on 173, only for wicketkeeper Sarfraz Ahmed to spill the chance tumbling to his right.
Left-armer Wahab also beat Root's outside edge in a lively opening burst, but received little support from a weary attack and, once Cook swept the day's first boundary off Zulfiqar Babar after 48 minutes, the runs flowed steadily for the tourists.
Root crunched Imran Khan through the covers before surviving a couple of leg-before shouts - the second of which saw Pakistan make their fourth incorrect review of the innings.
A reverse swept four off Shoaib Malik took Root to fifty, but it was predominantly singles and twos keeping the scoreboard ticking over during an extended morning session.
Cook reached the third double century of his Test career shortly before lunch, working Wahab into the leg-side for a couple, before moving on to the highest score by an England batsman in Asia shortly after the break.
Root was visibly frustrated to fall for 85 when he chased a wide Rahat Ali delivery and only succeeded in edging through to Sarfraz, and Wahab was rewarded for a brilliant display of reverse swing with the old ball when he had Jonny Bairstow trapped lbw for eight.
Cook, however, continued unabated, and once Ben Stokes survived a couple of early scares from Wahab he began to stamp his authority on proceedings with a series of leg glances and sweeps either side of the wicket.
The England 500, Stokes' half-century and Cook's 250 came up in a flurry of landmarks, before the Durham all-rounder perished for 57 charging down the track to Shoaib Malik.
By that stage England held an unlikely lead, which extended to 26 before Cook's marathon drew to a close with a chipped sweep off Malik falling straight into the hands of Shan Masood at backward square-leg.
Jos Buttler hit the first six of the innings in a lively 28-ball cameo which yielded 23 runs, but was caught out at extra cover attempting one shot too many off Babar.
Adil Rashid and Stuart Broad saw England through to stumps, leaving Cook with a decision as to whether they bat on in the morning or declare. He will feel entitled to a well-earned rest before making it.
England return to The SSE SWALEC in Cardiff in 2015 for Royal London One-Day Internationals against Sri Lanka and Pakistan.
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