Surrey won toss and chose to field first
Tom Kohler-Cadmore scored 62 off 48 balls as Yorkshire totalled 160-5
Surrey finished on 159-7 after needing five to win from the final over
Jamie Overton hit four sixes in his 40 off 21 balls before he was run out
The match was the first T20 meeting between Surrey and Yorkshire
Finals Day takes place at Edgbaston on 16 July
Yorkshire 9-2
A second major blow for Surrey.
Finn Allen tries to take a full-of-length ball over the leg side but there's a fraction of movement away and a bit leading edge flies in the air.
Jamie O with a second catch and both openers are back in the shed inside nine balls.
Yorkshire 7-1
Dan Worrall from the Pavilion End.
Yorkshire 7-1
Tom Kohler-Cadmore squeezes the final ball of the over past short-third man and it skips away for four.
Hard to remember an Oval wicket like this - grass all over it. A used one too.
Yorkshire 1-1
Image source, PA MediaOh this is a massive early blow.
A pretty ordinary delivery outside off that Adam Lyth goes back to cut.
It holds a little and he pops it up to short-extra.
Safe catch from Jamie Overton and 518 group stage runs walk off here for naught.
Adam Lyth and Finn Allen bounding out for Yorkshire.
Will Jacks is going to open up from the Vauxhall End.
Image source, Rex FeaturesFour Surrey bowlers have taken 10 or more wickets in the T20 Blast this season - but only one of them, Sunil Narine, will be playing tonight.
The West Indies leg-spinner has 13 victims so far and his economy rate of 5.91 is the best/lowest in the Surrey team.
The 34-year-old is also capable, though, of doing significant damage with the bat.
He hit 52 off 23 balls and 51 not out off 29 in home wins against Hampshire and Middlesex, and he'll want a return to that kind of form after failures in his last two innings.
Surrey v Yorkshire (start 18:30 BST)
Image source, Rex FeaturesWith Dawid Malan and Harry Brook away on England duty, Adam Lyth's role at the top of the Yorkshire batting order assumes even greater importance.
The left-hander has scored 518 runs in the competition, a total bettered only by James Vince, Shan Masood and Adam Hose.
He smashed 81 off 46 balls against Durham at the Riverside and made 69 and 52 in his last two innings.
The Vikings need him in the runs again at The Oval.
As well as this text commentary, there is ball-by-ball radio coverage available for you this evening, courtesy of our BBC 5 Live Sports Extra and BBC West Yorkshire Sport teams. Just click one of the audio promos at the top of the page to tune in.
This is the 20th season of domestic T20 cricket and tonight is the first time that these two sides have played each other in this format.
Surrey finished top of South Group after winning nine of their first 10 group games - the other was a no-result - but only one of their final four ended in victory.
Yorkshire made a stuttering start to the competition, with one win in their first four games - but a run of six victories out of eight last month helped them take fourth place in North Group.
They were beaten in their last two matches, but will look to turn that form around and reach Finals Day for the first time since 2016.
Surrey v Yorkshire Vikings (play starts 18:30)
Because England's T20 series against India begins tomorrow, both teams are shorn of key players this evening.
Surrey will be without skipper Chris Jordan, Jason Roy, Sam Curran and Reece Topley - although Ollie Pope and Jamie Overton are available.
It's not quite such a long list for Yorkshire, with batters Dawid Malan and Harry Brook absent, and England have allowed Vikings captain David Willey to take part in the game.
Acting Surrey captain Will Jacks has won the toss and chosen to bowl first.
Surrey: Jacks (capt) Burns, Pope, Evans, Narine, Overton, Hardie, T Curran, Atkinson, Worrall, Moriarty.
Yorkshire: Lyth, Allen, Kohler-Cadmore, Willey (capt), Fraine, Khan, Tattersall, Thompson, Hill, Revis, Bess.
Image source, Rex FeaturesThe BBC Weather forecast for London suggests that we have a fine evening ahead with the temperature remaining in the 20s.
For further information, please click here.
T20 Blast Finals Day is just 10 days away.
Tonight we begin the process of finding out which four teams will be heading for Edgbaston on the 16th.
First up, it's Surrey v Yorkshire, to be followed over the next three evenings Birmingham Bears v Hampshire Hawks, Lancashire Lightning v Essex Eagles and Somerset v Derbyshire Falcons.
Welcome to our coverage. Play begins at 18:30.