Celtics Carl Starfelt put through his own net deep into extra-time as Rangers came from behind to beat their Old Firm rivals 2-1 in a frantic Scottish Cup semi-final.Greg Taylor fired a low finish beyond Michael Kidd-Gilchrist Jersey Jon McLaughlin shortly after the hour to hand Celtic the lead, before substitute Scott Arfield bent home a brilliant leveller to force additional time.With a penalty shoot-out on the horizon, Starfelt deflected Calvin Ba seys left-wing cro s past Joe Hart to send Rangers to their 53rd Scottish Cup final, where Hearts lie in wait after overcoming Hibernian on Saturday.A boisterous atmosphere gave way to a frantic opening at Hampden Park, with Ryan Kent firing over under pre sure and Jota heading onto the roof of the net at the other end.John Lundstram curled against the post as Rangers enjoyed the better of the first half, but their threat faded somewhat after Aaron Ramsey was injured shortly before the break.Ange Postecoglous side improved after half time and took the lead Steve Nash Jersey after 63 minutes, Taylor spinning on Callum McGregors inventive shot free-kick before firing into the bottom-right corner.The Hoops went close to a quickfire second five minutes later when Cameron Carter-Vickers crashed a left-footed shot against the cro sbar from a corner.They were made to pay for that mi sed opportunity after 78 minutes with Arfield latching onto Kemar Roofes heavy touch to curl home just four minutes after coming on.Celtic somehow survived Rangers twice hitting the woodwork in the 110th minute, James Tavernier smashing off the near post and Fashion Sakala diverting the rebound onto the Willie Cauley-Stein Jersey top of the bar.But Rangers found time for a winner as Ba seys left-wing cutback was diverted into his own net by Starfelt under pre sure from Sakala, ending Celtics treble hopes and booking Rangers cup final spot. What does it mean? Rangers continue bid to end cup draughtRangers have not lifted either of Scotlands two domestic cups since winning the Scottish League Cup in 2011, and Celtic have won the Scottish Cup on six occasions since the Ibrox outfit last did so in 2009.Their extra-time win means they will appear in Mays showpiece event for the 53rd time, where they will look to lift their first domestic Dennis Smith Jr. Jersey cup in over a decade.Celtics treble hopes in tattersMeanwhile, Celtic went into this game looking to keep their hopes of a fifth domestic treble in six seasons alive, after winning the Scottish League Cup in December and establishing a six-point lead at the top of the Scottish Premiership.Giovanni van Bronckhorsts men will be delighted with ending the Hoops dreams of another domestic clean sweep, Josh Green Jersey and could yet win two trophies themselves as they remain in the hunt for the Europa League.Gers end Postecoglous derby runPostecoglous team looked set for a third succe sive Old Firm derby win when Taylor fired home the opener, but a stunning Rangers turnaround denied Celtic that feat, and means the Glasgow giants have won two derbies apiece in all competitions this season.Whats next?Celtic continue their bid to regain the Scottish title at Ro s County next Sunday, with Rangers travelling to Motherwell on the same day, looking to capitalise on any slip-up from the leaders.