The 35-year-old netted direct from a set-piece midway through the second half against TSW Pegasus, but went from hero to villain just six minutes later by hitting the bar from 12 yards.
However, Butt's side did eventually emerge 2-1 winners courtesy of an injury-time winner.
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The former Red Devil is currently on trial with South China and will have done his chances of impressing the club's owner Steven Lo no harm following the goal-scoring display.
"I enjoyed the goal. It was a nice goal. If I missed, maybe Mr. Lo would kill me," Butt joked.
"I enjoyed my time. There's a lot of things we need to discuss. A lot of things are positive. Hopefully the fans enjoyed seeing me play. Everything's good."
Butt made more than 260 league appearances for Manchester United from 1992-2004, scoring 21 times, helping Sir Alex Ferguson's side win six Premier League titles as well as three FA Cups and the Champions League in 1999.
He left Old Trafford to join Newcastle United, where he spent six years - featuring more than 130 times in the league - before departing last summer having guided the Magpies back into the top flight.
