It was the Magicians' maiden win this season and it came after eight matches and after 12 games in the Hockey India League.
It was the clash between the bottom-placed teams of the league and both were guilty of squandering chances, despite a goal being scored in each quarter.
The hosts took the lead in the 17th minute through a field goal when captain Glenn Turner pushed the ball on the rebound.
The debutants however reduced the margin in the 43 minute with a field goal from Mohammed Nizammudin.
Mumbai restored the lead in the 57th minute when Ravipal Singh combined with Sarvanjit Singh to make it 3-1.
However, the Terry Walsh-coached Lancers struck back a minute later through a field goal from Lucas Vila to keep the goal deficit to one.
The win gave Magicians, who played their last home tie, five points and took their tally to 13 points from nine games, while the Lancers pocketed a point to be at the fifth position with 17 points in 10 games.
