London Welsh will face Bristol for a place in next season's Aviva Premiership after Gordon Ross' late penalty handed them a dramatic victory over Leeds Carnegie.
Leeds had held a seven-point advantage from the first leg of their Championship semi-final and extended that to 13 with just 12 minutes left to play.
But Seb Steggman went over for a converted try in the 68th minute and when Oli Stedman crossed over three minutes later the Exiles led 26-20 on the day and trailed by just a single point in the tie.
Ross, who spent four years with Leeds from 2002 to 2006, then held his nerve with a shot at the posts with two minutes to play to make it 29-20 and hand London Welsh a 60-58 aggregate victory.
Justin Burnell's men will now face Bristol in the two-legged final after they beat Rotherham 22-11 on Saturday to secure a 39-25 aggregate win.