Time off the court also gave her the chance to rest a calf muscle injured in the Silver Ferns' 58-57 over-time world championship loss to Australia in Singapore.
Williams has played through ankle pain for some time, including at the gold medal-winning Commonwealth Games campaign in Delhi, and the operation cleaned the area around her ankle joint.
She missed five internationals last October - two against England in New Zealand and three against Australia in Perth, Adelaide and Melbourne, but was back to her physical best last night against the Steel, with a superb final quarter where she pulled off several trademark flying intercepts.
"When the feet don't want to move I throw my arms out and hope for the best," she laughed. "It was a good hit-out to be honest given the changes and the other team. It was far from perfect but there were patches there when everything felt smooth."
Magic were comfortable early on, building on their five-goal advantage after the first quarter to lead 24-11 on the back of a dazzling second period from Juliana Naoupu under the goal and former Steel defender Leana de Bruin at the defensive end.
But with both teams making numerous changes, the third quarter was dour, with the ball movement through the court from both ends resembling the Auckland motorway at rush hour.
The southerners won the quarter 8-7, although Magic still held a commanding 31-19 lead.
Williams said Magic were hoping to produce a more cohesive display in last night's late game against the NSW Swifts.
Swifts co captain Mo'onia Gerrard had been ruled out of the tournament after sustaining a right ankle injury in a training game last Saturday that will keep her idle for six weeks.
"It's good to get that first one out of the way and we won, but pre-season isn't going to mean much in four weeks' time when the season starts," Williams said.
Williams said her body was "pretty smashed" after last year's world championships in Singapore. As well as needing surgery to repair her ankle, the star defender was also battling calf and knee injuries. She was just as exhausted mentally following a painful one-goal overtime loss to Australia.
"I feel extremely refreshed both physically and mentally."
The Mystics held on to down the Canterbury Tactix by two goals, overturning a 12-14 first-quarter deficit to lead by three at half-time. Despite Kayla Cullen and Anna Scarlett starring, the Mystics found themselves battling to hang on to their four-goal lead in the fourth quarter as the Tactix reduced the margin to just one goal before eventually running out of time.
The West Coast Fever's reign under new coach Norma Plummer got off to an impressive start with a 40-33 victory over the Swifts while the Adelaide Thunderbirds scored a 41-32 win over the Central Pulse.