King was 2-0 up and seemingly cruising towards the next round but Teehan chipped away and pounced on missed opportunities from the Bradwell ace and sent it all the way. It was King despite that who moved through.
King quickly settled himself to his first tie at the Alexandra Palace as he claimed the first set in consecutive legs with an average of 82.
He continued this on in the next set claiming an early break of throw with an 11 darter but Teehan finally claimed his first leg of the match with a 1-darter and he attempted to shift the momentum in his direction but squandered nine darts at double to break throw and King sealed the set 3-1.
Teehan finally did claim a set claiming that break with double 12 and from there doubling his lead, he ended up winning it 3-1 with him hitting a fifth 180 and 76 on the bull to clinch it.
King produced a 128 checkout to break throw though which saw him let out a brilliant show of emotion and lead in set four and despite Teehan breaking with a 74 finish to level it up, King potentially landed the final nail in the coffin with a 116 checkout to break back and move one away.
King missed 111 for the victory and Teehan didn't fluff his lines breaking again with a 56 checkout. His spirit was lifted further as he edged the fourth set in a decider to send it all the way.
King though sent it one away again with a 24 checkout. Despite that, he missed one match dart and Teehan kept it alive and sent it to a tie-break which had to be won by two clear legs.
Teehan fluffed his lines on double 12 and King went one away. The Bradwell ace finally got over the line from there.
Click here for more information on the PDC World Darts Championship, which takes place at the Alexandra Palace between December 13 and January 1.
Friday December 20
Afternoon Session (1230 GMT)
4x Second Round
Darren Webster (91.28) 3-0 (82.34) Yuki Yamada (Second Round)
Mervyn King (88.36) 3-2 (86.4) Ciaran Teehan (Second Round)
Jonny Clayton v Jan Dekker (Second Round)
Ricky Evans v Mark McGeeney (Second Round)
https://twitter.com/OfficialPDC/status/1208033422951813127?s=20