England collapsed to a 10-wicket defeat inside three days against Pakistan in Dubai, their first Test loss for more than a year.
Pakistan paceman Umar Gul led the way with 4-63 as England, playing for the first time since claiming top spot in the world rankings with a 4-0 whitewash of India and unbeaten since Perth last December, were bowled out for 160 in their second innings.
That left Pakistan to chase a victory target of 15, a task their openers Mohammad Hafeez (15no) and Taufeeq Umar (0no) achieved inside four overs.
Gul ran through England's top order in the afternoon and was well supported by spinners Abdur Rehman (3-37) and Saeed Ajmal, whose 3-42 completed the second 10-wicket match haul of his career.
The three-match series continues in Abu Dhabi on January 25.
Facing a first-innings deficit of 146 and 40 minutes to bat until lunch, England lost captain Andrew Strauss in the fifth over of their second innings.
He was caught behind down the leg-side off Gul's bowling, a decision that was upheld on review despite Hot Spot showing no mark on Strauss' bat.
The situation quickly got much worse for the tourists in the middle session as Alastair Cook, Kevin Pietersen and Ian Bell went in quick succession.
Cook played too early at another short delivery from Gul to present wicketkeeper Adnan Akmal with another catch down the leg-side.
And Gul struck for the third time in his next over. Pietersen, having failed to score from his first seven balls, pulled the eighth straight to Rehman at deep square-leg.
That brought Bell to the crease on a king pair after his first-ball dismissal in the first innings. Bell did manage to get his first runs of the match with a lofted boundary off left-armer Rehman.
But that was all the Warwickshire right-hander had to show before Ajmal's doosra fooled him for the second time in the match. Bell played inside the line and was given out lbw, England burning their final review in a futile effort to overturn umpire Billy Bowden's verdict.
Coming together at 35-4, Jonathan Trott and Eoin Morgan briefly regrouped with a 39-run stand but Morgan was undone by Rehman just before tea, prodding at a ball that pitched in the footmarks to give Akmal his third catch of the innings.
Trott became bogged down on 49 early in the evening session, failing to score for 13 balls before finally losing patience against Gul and carving a big edge through to Akmal.
And Matt Prior soon followed, trapped by Ajmal's doosra playing back to become the spinner's seventh lbw victim of the match, one short of the Test record.
Gul thought he had completed a five-wicket haul when Bowden raised the finger to an lbw appeal against Swann, only for the batsman to be called back after the TV umpire told Bowden that Gul had overstepped.
From the 87-7, Swann and Stuart Broad took a positive approach to putting on 48 but it was only delaying the inevitable.
Broad holed out for 17 and Rehman followed up by having Chris Tremlett held at slip with his next delivery. Last man James Anderson avoided the hat-trick and hung around long enough for England to move into the lead and at least avoid the ignominy of an innings defeat.
The lead was 14 when Swann (39) sent a leading edge into the hands of cover to complete match figures of 10-97 for Ajmal.
Akmal's 61 had earlier allowed Pakistan to extend their first innings from an overnight 288-7 to 338 all out in the first 15 overs of the day.
Gul departed for a duck, driving to Morgan at point in Broad's opening over to continuing the collapse that had seen Pakistan lose Misbah-ul-Haq and Rehman late on day two.
Akmal forged useful stands with Ajmal and Aizaz Cheema for the final two wickets to frustrate England.
Ajmal contributed 12 to a ninth-wicket stand of 30 before off-spinner Swann had him caught via bat and pad. Umpire Bowden gave it out on the field, a decision that was upheld on review as replays were inconclusive.
Akmal went to his second Test half-century from 117 balls and put on 19 with Cheema before being last out, stumped giving Swann (4-107) the charge.