Deane Smalley blasted two goals in three minutes to sink Plymouth 2-1 and keep Oxford top of npower League Two.
The striker has had a torrid time in front of goal for the U's, managing just two goals in 29 appearances.
But he controlled Tom Craddock's cross from the left and fired past keeper Jake Cole in the 20th minute.
As Argyle were still trying to recover from that setback, Alfie Potter ran 40 yards through the middle before releasing Smalley on the right, and the centre forward drilled a shot just inside the near post.
Smalley had another effort saved, which would have given him a hat-trick, before making way at half-time for James Constable.
Argyle went close with Warren Feeney's glancing header soon after the restart.
Feeney also had a goal disallowed in the first half because he strayed offside when turned in Conor Hourihane's cross from the left.
But the Pilgrims did make a fight of it late on.
Substitute Robbie Willliams curled in a 25-yard free kick with 15 minutes to go for their first league goal this term.
And in a late rally, Onismor Bhasera almost snatched a point for the visitors with a drive that deflected just wide.