The Pakistan quick ripped through the visiting top order with a brilliant hat-trick, bowling full and fast to expose the poor footwork of the visiting batsmen, writes IAN McCULLOUGH.
Abbas struck with his fifth, sixth and seventh deliveries en route to figures of 6-11 from 11 overs to leave the 2016 champions staring down the barrel of a second successive LV= Insurance County Championship defeat following last week's dispiriting loss to Somerset.
Seamer Brad Wheal chipped in with 3-9 off 3.4 overs as Middlesex were skittled for 79 - their lowest score against Hampshire for 65 years - in response to Hampshire’s first innings total of 319.
But perhaps mindful of losing to Essex four years ago after enforcing the follow-on, skipper James Vince opted to bat again as the hosts closed the day a mammoth 444 in front with Sam Northeast (99 not out) and Ian Holland (90) both closing in on their centuries following a 202-run stand.
If they reach three figures on day three, they will be the fourth and fifth Hampshire batsmen to score a Championship hundred in the first two innings of the 2021 campaign.
Hampshire had earlier added 38 runs to their overnight total, led by Kyle Abbot's fighting 58, with Steve Finn wrapping up the tail before lunch to post figures of 4-95 in his first red-ball appearance in almost two years.
But any hope Middlesex had of posting a challenging response were dashed after just six overs when they slumped to 14-5 - Abbas taking all five wickets in the space of an astonishing 17-ball spare.
At one stage Abbas boasted figures of 5-3 from four overs.
Max Holden was the first of his victims, off the fifth ball of his opening over, before Nick Gubbins departed the very next delivery.
Captain Steve Eskinazi then edged behind to Lewis McManus for a duck from the opening delivery of Abbas' second over to present the 31-year with his maiden first-class hat-trick.
Robbie White and Martin Andersson were then trapped lbw without scoring by Abbas as a shell-shocked Middlesex went to lunch at 23-5.
Sam Robson, a centurion last week at Lord's, became Abbas' sixth wicket when he was caught behind for 18 shortly after the restart before Abbott rearranged Toby Roland-Jones' stumps four balls later.
Wheal then ran through the visitors' lower order with only Nathan Sowter showing any signs of resistance with an unbeaten 24.