The Argentinian attacking midfielder showed his class throughout the match, with one assist and one goal as well as a plethora of great touches.
An early warning sign for Wellington came in the 11th minute when Martinez saw his long-range free-kick swerve just over the crossbar. A minute later an attack launched by Martinez saw the ball in the back of the net, but the assistant referee incorrectly ruled the goal out for offside.
Martinez curling shot had ricocheted off the post, Terry Antonis was first to the rebound but his shot was straight at Wellington 'keeper Glen Moss, the ball rebounded again this time to Brendon Santalab who headed home from six yards out. Replays showed that neither Antonis nor Santalab were offside but the match remained goalless.
The Wanderers seemed unperturbed and had their goal eight minutes later after Martinez produced a wonderful turn before sliding in Santalab for his seventh goal this season.
Santalab returned the favour in the 58th minute, when he slid the ball across for Martinez who made no mistake with a smart first-time finish past Moss to make it 2-0.
The score threaten to get out of control in the 65th minute when Santalab scored his second of the match and the Wanderers' third after Antonis had pounced on poor defending for the Phoenix.
Wellington maintained some respectability by pulling a goal back via a Shane Smeltz penalty - his 90th A-League goal - in the 70th minute, but the good work was undone after he was sent-off for a second yellow card five minutes later.
Western Sydney move up to fifth on 21 points, momentarily, with Perth Glory (21pts) and Newcastle Jets (20pts) playing each other later on Saturday.
Coach Tony Popovic was pleased to come away with an invaluable three points in a season where Western Sydney have struggled for wins, with nine draws from 18 matches.
"It was a tough game, everything we expected," he said.
"We came up against a very good team, a dangerous team and we defended very well for large parts of the game.
"On attack, we always felt we were a threat throughout the match, and tonight we put away those chances."
Co-coach Des Buckingham said the Phoenix's inability to convert opportunities into goals had proven costly.
"We're disappointed by the manner in which we played. We had good spells in the game where we controlled a lot of the possession, but we never looked really effective with it," he said.
"In that final third again, it's just an area we really need to nail down."
