The world number two hit a brilliant century in the deciding frame to secure his place in the next round, where he will meet Anthony Hamilton.
It was far from plain-sailing for Trump though and he faced an ignominious exit from the first world ranking event of 2013 after he let slip a 3-1 lead to fall behind 3-4 against the former world number three.
Wattana had a chance in frame number eight, but Trump fought back to force a decider, during which a break of 106 sealed his progress.
"I should have gone 4-1 up but had a kick," said Trump. "Then he went all out attack and played well to go 4-3 up. In the last two frames I played some good snooker. In the decider I knew I had to go for the long red. I've missed a few of those by a long way but I hit it well.
"Then I just had to keep my composure. It was such a big match because it's a good arena so no one wants to go out first round. If I keep making breaks like that under pressure then I'll have a chance."
In the third round, Ali Carter recovered from 3-1 down to topple Fraser Patrick 5-3, while Matthew Stevens's passage into the fourth round was altogether more straightforward with a 5-1 win over Jamie Burnett.
Kurt Maflin, Barry Hawkins and Andrew Higginson completed the day's list of players through to the last 16.
Earlier, veteran Jimmy White was knocked out by Dominic Dale, who won 5-3 in their second round encounter.
Six-times World Championship finalist White gained the snooker he needed and cleared the colours to move within a frame of Dale, but the latter took the eighth frame to seal a place against Mark Allen, who beat Nigel Bond 5-2.
Ding Junhui, Shaun Murphy and Mark Williams came through their second round matches and will face Marcus Campbell, Robert Milkins and Michael Holt respectively.
ROUND THREE RESULTS:
FRASER PATRICK 3 v 5 ALLISTER CARTER
XIAO GUODONG 4 v 5 KURT MAFLIN
ANDREW HIGGINSON 5 v 1 STUART BINGHAM
MATTHEW STEVENS 5 v 1 JAMIE BURNETT
DECHAWAT POOMJAENG 2 v 5 BARRY HAWKINS
ROUND TWO RESULTS:
JUDD TRUMP 5 v 4 JAMES WATTANA
JAMIE COPE 0 v 5 ANTHONY HAMILTON
MARTIN GOULD 1 v 5 FRASER PATRICK
ALLISTER CARTER 5 v 0 RORY MCLEOD
MARK DAVIS 2 v 5 XIAO GUODONG
TOM FORD 1 v 5 KURT MAFLIN
MICHAEL HOLT 5 v 1 TIAN PENGFEI
MARK WILLIAMS 5 v 1 MARTIN O'DONNELL
NEIL ROBERTSON 5 v 0 DANIEL WELLS
PETER EBDON 3 v 5 MICHAEL WASLEY
ANDREW HIGGINSON 5 v 4 ZHANG ANDA
STUART BINGHAM 5 v 1 ROD LAWLER
GRAEME DOTT 5 v 3 LIANG WENBO
RYAN DAY 4 v 5 DAVE HAROLD
ROBERT MILKINS 5 v 4 CHEN ZHE
SHAUN MURPHY 5 v 1 BEN WOOLLASTON
JOHN HIGGINS 3 v 5 PETER LINES
KEN DOHERTY 5 v 4 ADAM DUFFY
MARCO FU 5 v 4 MATTHEW SELT
RICKY WALDEN 5 v 3 ALFIE BURDEN
MATTHEW STEVENS 5 v 3 PANKAJ ADVANI
JAMIE BURNETT 5 v 4 MARK JOYCE
MARK KING 5 v 3 BARRY PINCHES
STEPHEN MAGUIRE 5 v 3 ALAN MCMANUS
MARK ALLEN 5 v 2 NIGEL BOND
DOMINIC DALE 5 v 3 JIMMY WHITE
FERGAL O'BRIEN 2 v 5 DECHAWAT POOMJAENG
BARRY HAWKINS 5 v 0 SAM BAIRD
DING JUNHUI 5 v 4 LIU CHUANG
MARCUS CAMPBELL 5 v 3 JAMIE JONES
JOE PERRY 5 v 0 SIMON BEDFORD
MARK SELBY 5 v 2 THEPCHAIYA UN-NOOH