Doncaster Rovers saw their lead at the top of League Two slip to two points after succumbing to a 2-1 defeat at Wycombe Wanderes.
Alfie May scored a fine solo strike but it was sandwiched by two efforts from Luke O'Nien.
Rovers manager Darren Ferguson said: "I'm disappointed with the result and the performance, Wycombe deserved the win.
"There are certain things I demand from my players, it wasn't a performance I was expecting from them. I like to be able to enjoy watching my team play and I didn't enjoy it today.
The damage could have been worse for Rovers had Plymouth beaten Colchester - although the second-placed side's goalless draw moved them to within a win of leapfrogging Darren Ferguson's men.
Rovers, already promoted to League One, could wrap up the title with a home win over Exeter City next week, if Plymouth slip up at home to Crewe Alexander.
Ferguson's men finish the season against relegation threatened Hartlepool United, who sit one point above the drop zone.