Pietersen back in the spotlight
Former England stars Kevin Pietersen and Andrew Flintoff could both feature at Finals Day after the squads were unveiled on Friday.
For Pietersen it represents a final chance to occupy centre stage in a season that has so far been something of a damp squib.
Having had his international career unceremoniously ended by the England and Wales Cricket Board earlier this year, Pietersen hoped some eye-catching displays for Surrey would keep him in the spotlight and make a mockery of that controversial decision.
Instead, talk of playing four-day cricket has evaporated and his short-form displays have been less than stellar, with a top score of 39 in 11 T20 innings.
But Pietersen has made a career of rising to the big occasions and, with a record crowd of 23,000 expected, he will have one final chance to grab the headlines.
Surrey face hosts Birmingham in the first semi-final, with Lancashire and Hampshire meeting in the second match of the day.
Although playing in front of a partisan Edgbaston crowd, Surrey coach Graham Ford feels his side, who boast the competition's top run-scorer Jason Roy, are well primed for the occasion.
"I'd like to think we have a little advantage there," he said.
"Our lads have played in front of magnificent crowds at the Kia Oval with great atmosphere so playing in front of a big crowd on the big day should be a little easier on them, some of the other sides maybe haven't had that same support and atmosphere that we have."
Pietersen will be joined at Edgbaston by another former England captain, Lancashire all-rounder Flintoff.
Flintoff made his professional comeback this season after four years of retirement but featured just twice before a calf injury laid him low.
He is therefore an outside bet to make the team, which should include Test stars Jos Buttler and James Anderson, but player-coach Glen Chapple is happy to have Flintoff's experience on hand.
"He has found his fitness late, so he will be coming to Edgbaston with us," Chapple told the Manchester Evening News.
"His injury was always going to be touch and go for finals day, and that was the worry. Now he is about right, albeit he hasn't played much cricket, but he will be coming as part of the squad.
"You would always back him under pressure. We know he has plenty of bottle when it comes to it."
Two-time winners Hampshire are the side with the proven pedigree, having reached the last-four for five consecutive years.
They won the competition in 2010 and 2012 but the absence of overseas stars Kyle Abbott and Glen Maxwell will be a major blow.
Owais Shah returns to bolster their line-up, but captain James Vince will shoulder much of the burden.
For hosts Birmingham, meanwhile, there is a genuine feeling of anticipation after the Bears qualified for Finals Day on their home patch for the first time.
Edgbaston has become the go-to venue for the marquee event, hosting for the sixth year, but this is the first time the home side are present at the showpiece
Chief executive Colin Povey said: "NatWest T20 Blast is one of the biggest days out in British sport. Last year's Finals Day at Edgbaston set a new record attendance for the tournament and we're thrilled to beat that this year, with around 23,000 spectators set to be in attendance on Saturday.
"Ticket sales before the quarter-final stage were already strong, but the Bears winning through to our first home Finals Day in-front of our members and supporters has generated a great buzz around the club."
Birmingham Bears: TBA
Hampshire: James Vince (capt), Will Smith, Owais Shah, Jimmy Adams, Sean Ervine, Sean Terry, Michael Carberry, Danny Briggs, Chris Wood, Adam Wheater, Joe Gatting, Liam Dawson, Michael Bates, James Tomlinson, Matt Coles.
Lancashire: Paul Horton (capt), James Anderson, Tom Bailey, Karl Brown, Jos Buttler (wkt), Jordan Clark, Steven Croft, Alex Davies (wkt), Andrew Flintoff, Kabir Ali, Simon Kerrigan, Arron Lilley, Stephen Parry, Ashwell Prince, Tom Smith, Usman Khawaja.
Surrey: Gary Wilson (capt), Zafar Ansari,Gareth Batty, Rory Burns, Steven Davies, Jade Dernbach, Matthew Dunn, Aneesh Kapil, Azhar Mahmood, Kevin O&'Brien,Robin Peterson, Kevin Pietersen, Jason Roy, Chris Tremlett.