Shane Bond is out of Sunday's televised Friends Provident Trophy clash against the Gloucestershire Gladiators after breaking down during a heavy defeat against the Somerset Sabres under the Rose Bowl floodlights.
The injury-prone New Zealander suffered an ankle strain against Yorkshire at Headingley last week and in his first one-day appearance at the Rose Bowl he was only able to bowl five overs before limping off with a calf strain.
It left Hampshire desperately short of firepower and unable to defend a total of 286-4 that looked more than enough when Sean Ervine yorked Marcus Trescothick, the Somerset captain in the absence of Justin Langer (migraine), in the second over of the visitors' reply.
Hampshire were still confident when Greg Lamb held on to a smart return catch to see off Craig Kieswetter.
But James Hildreth capitalised on Bond's injury and Dimitri Mascarenhas's absence by making a nonsense of the decision to leave him out of the England Lions team for next week's match against New Zealand at the Rose Bowl.
The second one-day hundred of the 23-year-old's career helped sentence Hampshire to a five-wicket defeat with nine balls to spare.
He put on 159 in 23 overs with South African all-rounder Zander de Bruyn during his unbeaten 112 from just 90 balls, which included 12 fours and two sixes.
Hampshire's hopes were raised when off-spinner Lamb dismissed de Bruyn (79), Ian Blackwell (21) and John Francis, who was back at the Rose Bowl at this level for the first time since leaving in 2003, during four overs from the Pavilion End.
Blackwell was dropped twice and Wes Durston once but Somerset completed a second Friends Provident Trophy win in 12 days against the Hawks, whose hopes of qualifying for the quarter finals are now in doubt.
After being put in by Trescothick, Hampshire began their first day-night match of the season well by compiling their biggest 50-over score since the opening Friends Provident Trophy group game of last season's competition.
Michael Lumb pulled Somerset's seamers ferociously, hitting five fours and a six on his way to a 67-ball 55 during his opening stand of 83 with the dependable Michael Carberry.
The opening pair made a solid start against the seaming ball before Pietersen cracked a 59-ball 62.
Pietersen's first boundary went to the rope from the toe of his bat but he followed that with a typically dynamic display of clean hitting after arriving at the crease in the 24th over.
He put on 99 in 16 overs with John Crawley in his first Hawks appearance since last August's Friends Provident Trophy final defeat at Lord's.
Crawley, having been dropped on 13 off the medium pace of de Bruyn by Phillips at deep mid-wicket, made the pair of them pay with sixes against each.
Pietersen made de Bruyn suffer further with a maximum hit over long off in the same over that Crawley was put down.
Crawley eventually nicked a Steffan Jones delivery that followed his 54-ball half-century.
But Pietersen still had more to give and he drew gasps from the Rose Bowl crowd when he sent de Bruyn for the biggest hit of the night over the big deep mid-wicket boundary on the Nursery side of the ground.
He was out in the same over, the 44th, after stepping across his stumps and missing an attempted sweep against the medium pace of Pothas's former Gauteng teammate.
Sean Ervine struggled when he arrived at the crease with ten overs to go but after getting his eye in he blitzed his way to a 36-ball 55*.
He batted far more impressively than he bowled, hitting De Bruyn and Phillips for sixes over mid-wicket and cow corner.
After being joined by Chris Benham when Pietersen departed, the fifth-wicket pair added 73 runs in less than seven overs.
But in the end it was not nearly enough.
Captain Nic Pothas was left a frustrated figure.
He said: "We thought 250 would be a good target so getting 286 was a bonus.
"Everyone batted well for us but losing our strike bowler when there was a small boundary on one side was too much.
"We could have executed our plans against James Hildreth a little better. We let him score a lot of runs square of the wicket which we knew was one of his strengths.
"But if we had an extra frontline bowler it could have been very different."
Hampshire's next FP Trophy south/west group match against the Gloucestershire Gladiators starts at 12pm at the Rose Bowl on Sunday.
Hampshire bowling: Bond 5-1-24-0, Ervine 10-0-88-1, Tremlett 10-1-45-0, Taylor 9.3-0-48-0, Lamb 9-0-47-4, Pietersen 5-0-34-0
Somerset bowling: Willoughby 10-3-33-0, Jones 10-0-59-1, Phillips 9-0-62-1, Blackwell 7-1-38-0, Trego 7-1-34-1, de Bruyn 7-0-56-1
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