Judd Trump reeled off three frames in a row against defending champion Ronnie O'Sullivan to make sure the opening session of their Betfair World Championship semi-final ended level.
Four-time world champion O'Sullivan took charge in the early stages of the encounter moving 4-1 ahead, but his younger opponent showed great character and tactical nous to fight his way back into the contest.
After his epic last eight victory against Shaun Murphy, Trump has vowed to go out and "scare" O'Sullivan, but it was the 37-year-old who sent out an early warning in the race to 17.
He produced a wonderful positional shot from red to black by the right middle pocket before making a break of 65 in the opening frame.
The second was more cat and mouse, although the 23-year-old left-hander from Bristol responded before missing an easy red which allowed his opponent to counter-punch and level the scores at 68 points apiece.
Referee Michaela Tabb tossed the coin before respotting the black and, after a both players missed opportunities, it was Trump who kept calm to come out on top after a thrilling 32 minutes of pure drama.
In the third, the 'Rocket' potted five red and red blacks before missing a tight red to the middle much to the disappointment of a packed Crucible crowd. However, it wasn't too long before he was back amongst the balls making a break of 34 this time to help him move 2-1 up.
O'Sullivan, who crushed Stuart Bingham 13-4 in the quarter-finals, comfortably won the last frame before the mid-session interval with an exhibition of break-building in making 75.
After the break O'Sullivan took advantage of a poor safety shot from Trump to make a quick-fire 89 and move 4-1 ahead but, with the four-time champion threatening to pull away, Trump showed his resilience by potting a pressure yellow on his way to a break of 51 to reduce the deficit.
World No 3 Trump then opened up with 31 points in the next before missing a red to the middle which allowed O'Sullivan to respond with 51. But a scintillating long red followed by a clever snooker in behind the green allowed Trump back in to complete the job.
Trump, who leads their head-to-head record 6-5, made sure the session ended all-square with a break of 72, before both players were given a standing ovation on their way out of the auditorium.
Walden on top
Jostling for the right to take on O'Sullivan or Trump are Chester's Ricky Walden and Kent's Barry Hawkins and it was the former who made much the better start on Thursday evening.
Hawkins had speculated he might suffer from nerves during the single-table format and that seemed very much the case as he managed a best break of 19 in the first four frames.
By contrast Walden looked comfortable and ended up rattling in two centuries (105 & 119) and a break of 91 as he opened an early 6-2 advantage.