Partick Thistle suffered more play-off penalty woe as Lewis Vaughan’s spot-kick fired Raith Rovers into a promotion decider.The Jags were on course to reach their second successive cinch Premiership play-off final after David Mitchell saved Raith’s first penalty from Scott Brown at Stark’s Park after a 3-3 aggregate draw.But Jack McMillan missed the target and Ricco Diack hit the post to allow long-serving Raith forward Vaughan to secure a 4-3 shoot-out win.Ian Murray’s side now have the chance to end a 27-year absence from the top flight when they take on either St Johnstone or Ross County over two legs next week.Thistle will again need to get over their disappointment and go again 12 months on from losing on penalties to County after letting a three-goal lead slip in the final.Blair Alston had netted a first-half double either side of a Ross Matthews goal to cancel out Raith’s 2-1 first-leg lead and set up an intriguing further 75 minutes of action.The Thistle midfielder had come off the bench to net a late lifeline in the first leg – four of his six goals this season have come against Raith – but he went off injured midway through the second half.Alston was close from long range early on and went one better in the 16th minute when his 25-yard free-kick took a nick off Brown and went out of the reach of goalkeeper Kevin Dabrowski.Thistle appeared to take a step back after levelling the aggregate score and Raith took advantage on the half-hour mark after a lengthy spell of possession. Matthews ran untracked from the edge of the box to meet fellow full-back Liam Dick’s back-post cross and headed home from six yards.The Jags regained the initiative and Scott Robinson was causing problems before setting up their second goal in first-half stoppage-time.Centre-back Dan O’Reilly was allowed to carry the ball up to the halfway line unchallenged and launch an aerial ball forward. Brian Graham and then Robinson helped the ball on and Alston netted on the rebound after Dabrowski had stopped his initial effort.Both sides looked more convincing when on the front foot and each enjoyed spells of superiority after the break.Rovers captain Brown was at the centre of the action, twice coming close from outside the box either side of producing a brilliant double goal-line clearance to deny Aaron Muirhead and then O’Reilly following a corner.Dabrowski saved well from McMillan and Harry Milne and again the momentum swung before Graham made an important headed block from Sam Stanton’s strike.Graham had a glorious chance to score his 27th goal of the season and win the game with the last kick of the 90 minutes but the Thistle captain lost his footing and shot over.Thistle substitute Lewis Neilson curled just wide at the start of extra-time but Raith had the better of the first period with Stanton denied by Mitchell.Thistle were back in the ascendancy after the break. Graham’s shot was blocked in the goalmouth before Luke McBeth hooked just wide from the resulting corner.The Jags continued to look the likelier side and Dabrowski dived to his left to make a brilliant stop from Milne’s bouncing long-range effort to set up penalties.