Northamptonshire seamer Ben Phillips took his second List A four-wicket-haul, removing Kevin Pietersen, John Crawley, Warne and Chris Tremlett on his way to four for 48.
James Middlebrook was the main contributor with the ball, taking two for 27 off 9 overs, but South African pace bowler Dale Steyn also contributed with three for 34 amid no-balls and wides.
Northamptonshire won the toss and batted, but 215 for 7 was never going to be enough on a fine Old Trafford pitch, where Lancashire's Mal Loye smashed 94 not out with ten fours and three sixes.
It was the Africans who made the most impact, as Zander de Bruyn's 62 laid the foundation for a target of 191 that was to become too large for the visitors, while the exiled Zimbabwean spinner Ray Price took four wickets for 21.
With Nottinghamshire's overseas players, Stephen Fleming (5) and David Hussey (2) being removed early by Sri Lankan fast bowler Chaminda Vaas, the visitors were in trouble, and Price and de Bruyn – who came on first and second change – tied them down effectively, with 4–21 and 0–20 respectively.
Dominic Cork was the most punishing bowler, taking four for 14 off nine overs (including five wides) as Gloucestershire whimpered to 86, as veteran wicketkeeper Mark Alleyne top-scored with 24 not out.
Jon Lewis, who had earlier on in the day been called up to the England ODI squad to meet Bangladesh and Australia, took three for 40, but it was not enough to stop Lancashire from cruising to the target with nearly 25 overs to spare.
Six wides from Chris Tremlett, who conceded 51 runs off his eight overs then cost Hampshire the game after Shaun Udal had taken three wickets to set Northamptonshire Steelbacks back to 135 for 5.
However, Worcestershire Royals' reply were hampered by wickets falling everywhere, along with lack of responsibility to keep the run-rate up, as Vikram Solanki made 40 off 66 balls and Zander de Bruyn 55 off 74 – too slow to chase 225 in 44 overs.
In reply, Nottinghamshire were always going to be in trouble after crashing to 86 for 4, Weekes ripping out two wickets, but Samit Patel and Chris Read lifted them to 231 for 5 before Alan Richardson removed them both.
Winning the toss and batting, Gloucestershire crumbled from 53 for 0 to 55 for 4 in a collapse very reminiscent of what happened at their home ground on that same day in the England vs Australia game, but 63 from Mark Hardinges rescued them to a competitive total of 215 for 9.
However, Fleming and Mark Ealham put the chase back on with a partnership of 75, before Hampshire struck again with wickets in successive overs, and then Shaun Udal had Greg Smith lbw for 6.
Worcestershire started creditably, snaring the wicket of Robert Croft in the second over, but Glamorgan sent out another pinch-hitter in Alex Wharf who made 38 before he was bowled bu David Leatherdale who took two for 35.
Having been put in to bat by Worcestershire Royals after rain delayed the start, Kabir Ali dug out a wicket with his first ball, and despite 51 from Matt Windows Gloucestershire still only posted 168 for 9.
The Royals' innings struggled from the outset, when Stephen Moore was dismissed for a duck, and despite 52 from Graeme Hick, Worcestershire imploded to 185 for 9 at one point, with Bilal Shafayat taking four for 33 with medium-pace bowling.
Hardinges was the main culprit as Hampshire lost their last nine wickets for exactly 100 runs to post a total of 178, despite Nic Pothas, Sean Ervine and Shane Watson all making at least 40.
In reply, William Weston and Matt Windows paired up for 106 runs for the second wicket, and not even Chris Tremlett, who took three for 34, could stop Gloucestershire from reaching the target with more than ten overs to spare.
Taking a fancy to young medium-pacer Chris Wright, the 21-year-old slashed five sixes and seven fours to make 85 not out – only his fourth fifty in List A cricket.
Only eight overs of play were possible before the umpires called off the game, and in that time Essex lost both openers but still made 53 for 2 – a score including six wides bowled by the Nottinghamshire Outlaws bowlers.
The Gladiators won the toss and got immediate success, as Jon Lewis dismissed Mal Loye with the second ball of the day, but pretty much everything went against Gloucestershire from then on, as Stuart Law, Mark Chilton and Andrew Symonds flayed the bowling to all corners.
Having been put in to bat by Glamorgan Dragons' captain Robert Croft, they got themselves to 155 for 2 thanks to fifties from Usman Afzaal and David Sales, and to finish the innings off Bilal Shafayat and Riki Wessels unleashed themselves with quick knocks.
Bandara then got the wickets of Stephen Moore and Vikram Solanki with successive deliveries, but Chris Gayle guided the hosts home with an unbeaten 53 off 70 balls, as Worcestershire won with more than 20 overs to spare.
They were put in to bat by Nottinghamshire Outlaws and after losing Kadeer Ali and Ramnaresh Sarwan for ducks, Steve Adshead and Craig Spearman rebuilt with a 60-run third-wicket stand.
Jon Lewis broke through their defences, however, shattering Ealham's stumps as he was bowled, and when Anurag Singh departed for 41, Nottinghamshire's task looked steep.
However, it was Worcestershire Royals who won the toss and batted first, Stephen Moore and Vikram Solanki (coming in for Chris Gayle who retired hurt) adding 103 for the first wicket.
Andre Adams took three wickets as Worcestershire lost four for one solitary run, but Smith hung in there with number 11 Nadeem Malik and ensured a total of 240 for 9.
The Lightning fell to 94 for 5, with four Middlesex bowlers getting one wicket each, and despite all-rounder Glen Chapple recording his first one-day half-century of the season with 71, and they were bowled out for 219 an over before the end.
Winning the toss and bowling first, Gloucestershire's spinners Malinga Bandara and Mark Hardinges shared four for 87 in their 18 overs after the opening bowlers Jon Lewis and James Averis went wicketless.
The visiting Nottinghamshire Outlaws batted first, and after a slow start where Anurag Singh and Stephen Fleming had accumulated forties to see them to 101 for 3, Hussey hit loose.
When they came back to bat, Hampshire were set 165 to win – and duly lost six wickets for 58 runs, Gareth Clough having two men bowled and captain Shane Warne lbw.