Dawson held his nerve to hit the winning runs for Hampshire
FP Trophy winners Hampshire got their Pro40 campaign off and running with a final-ball floodlit win over Yorkshire.
Jaques Rudolph (79) and Andrew Gale (54) helped the Tykes post a decent target of 232-6 at the Rose Bowl.
But, triggered by 51 at the top of the order from Michael Lumb, contributions came all the way down as the home side finally reached their target on 233-5.
And Liam Dawson kept his cool off the last ball to sentence Yorkshire to a second defeat in three games.
Earlier, Rudolph's solid but unspectacular innings provided the framework for Yorkshire before the South African was dismissed towards the end of the innings trying to accelerate the run rate.
Rudolph and fellow opener Andrew Gale (54) provided Yorkshire with a steady start as the traditionally temperamental Rose Bowl wicket showed little sign of movement.
Gale survived an appeal for a run out and was then dropped by Hampshire wicketkeeper Tom Burrows. But his luck finally ran out moments after bringing up his 50 as he skied Billy Taylor's delivery to mid on.
But, with Yorkshire skipper Anthony McGrath missing due to a damaged thumb, Rudolph remained a constant. And, despite the middle order wobble, he brought his 50 up in the 27th over on the way to propelling the Tykes towards the 200 mark.
But, with four overs remaining, Rudolph hit a huge six off Imran Tahir, then tried to repeat the feat the following ball only to hit the off spinner straight down the throat of Dominic Cork.
Rudolph's demise left the overriding feeling that Yorkshire were short of runs.
That certainly looked to be the case when Lumb, the son of a Yorkshireman, and fellow opener Jimmy Adams (44) put on 95 to steer their side well above the required run rate.
But England spinner Adil Rashid came on to remove Adams, thanks to a fine catch from Tim Bresnan. Then Lumb fell to some fine glove work from keeper Gerard Brophy off the bowling of David Wainwright. And, at 147-2, with 86 needed off 10 overs, the chase now looked a tall order.
But Michael Carberry (39) and Sean Ervine responded with some big hits. And, although Dimitri Mascarenhas (34) and Ervine (41) were both run out by Adam Lyth, the relatively inexperienced Dawson proved up to the task.
Coming in with three balls remaining, he took a quick two to tie the scores before flicking Matthew Hoggard off his pads to scamper to victory.
Hampshire batsman Jimmy Adams told BBC Radio Solent:
"Having lost against Sussex a few weeks ago it was nice to get ourselves on the board.
"We were pretty disappointed after the game at Northants last week as we didn't do ourselves justice and were well below par.
"There were areas we could do better but to win off the last ball is always a great feeling."
This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.