Hampshire must win their final game of the season at Derby to win promotion to the National League's first division after suffering a third successive defeat in a Lord's thriller.
Paul Terry's side take on the Derbyshire Scorpions knowing that another defeat could see them miss out on promotion.
The fourth-placed Middlesex Crusaders are now just two points behind and take on the Durham Dynamos at Chester le Street, where defeat will see Hampshire promoted, regardless of the result at Derby.
At Lord's yesterday Middlesex beat the Hawks by six wickets with just one ball to spare to keep their season alive.
Four months ago Middlesex won in the last over at the Rose Bowl and yesterday they managed a repeat.
The home side had needed 76 for victory with ten overs and eight wickets left and with three overs left they needed 26, when Chamnida Vaas stepped up to bowl his last over.
Successive boundaries for Ed Joyce ensured that 14 runs were needed off the last two overs.
Alan Mullally began it by swinging the game back in Hampshire's favour but successive balls at the end of the penultimate over and the beginning of the 45th sealed Middlesex's win.
Twelfth man James Hamblin, who was on as a substitute for Chris Tremlett, lost sight of the ball as it came out of the sun and dropped Owais Shah at long off off Mullally's final ball.
Then Dimitri Mascarenhas, who had haemmoraged runs at nine an over in his previous five, stepped up to bowl the last over with Shah still on strike.
Shah smashed it for his only six, over the gap beteeen long off and deep extra cover, and Middlssex were left needing three runs from the last five balls.
Hampshire hopes were raised when Shah clipped the next ball straight to Shaun Udal, at short mid wicket but James Dalrymple squeezed out two singles, including the winning run to point.
The match would have gone to the final ball if Simon Katich had held on to a diving effort at mid on to remove Joyce - he just manged to get his fingertips to the fourth ball of the final over, failing to stop Middlesex levelling the scores.
Both sides totalled their highest scores in previous matches between the counties and Middlesex's 278-4 was largely down to Paul Weekes, whose 104 was only his second ever century in the competition.
Katich and Nic Pothas had shared Hampshire's highest opening stand of the season as the Hawks amassed 277-7 Katich and Pothas put on 144 in 26 overs after Middlesex had won the toss.
Pothas set the pace, looking as good at the crease as he has ever done for Hampshire in near perfect batting conditions.
The South African reached his fifty from 54 balls with successive boundaries off Ben Gannon, clearly relishing in the opener's role that he adopted on his recall to the National League side against Lancashire a week earlier.
A succession of thumping cover and off drives and square cuts were the highlights of his 78.
His two innings against Lancashire and Middlesex are his highest in the National League for Hampshire.
He was first out yesterday, holing out to long on for a run-a-ball 78, of which more than half the runs came in boundaries
Katich's 106, meanwhile, was his second one-day ton for Hampshire and his second in five games, following his 106 against Somerset in the record-breaking total of 335-9 at Taunton last month.
The Australian reached his hundred in just 112 balls before he was bowled as he attempted to cut.
It was a memorable way for him to mark his first game at Lord's and Katich's hundred took him level with John Crawley's aggregate of 672 National League runs for the season.
Never before have two Hampshire players scored more than 600 runs in the competiton in one season, but Crawley failed to add to his tally. The Hampshire skipper needed five more runs to take him past Robin Smith's aggregate of 676 in 1984.
But he was bowled first ball by Weekes, who took 3-2 in seven balls, and both he and Katich now need 49 runs at Derbyshire to surpass Chris Smith's 19-year-old record of 720 runs in a Sunday League season.
Crawley batted down at five, allowing Mascarenhas to open his shoulders at four after Derek Kenway was caught at deep mid wicket in the 36th over, having put on 61 with Katich.
Mascarenhas finished unbeaten on 27, which he smashed from 21 balls, and added 43 in just four overs with Will Kendall after Kenway and Crawley had departed.
Kendall, playing his first first team game for two months following the departure of Somerset-bound John Francis, hit a huge six over wide long on on the way to 26 from 21 balls.
He was run out going for a second, beaten by Simon Cook's throw from long off, after doing his bit to help smash 52 off their last five overs.
Then Lawrie Prittipaul, who was caught at deep mid wicket, and Udal, caught at long on by Ben Hutton, were dismissed in successive overs as Hampshire made their seventh highest ever National League score.
Sadly, it did not prove to be enough.
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