Burnley opted for Brian Laws after failing to agree compensation for O'Driscoll and Doncaster celebrated holding on to their boss with some champagne soccer.
The first threat came from Watford when James O'Connor blocked a volley from Lloyd Doyley in the second minute but it was all Rovers after that.
Skipper Brian Stock returned to boss the midfield after four months out following an ankle operation and it needed some excellent goalkeeping from Scott Loach to keep Rovers out.
Loach did well to save at full stretch from James Coppinger in the third minute before Dean Shiels hit a great chance wide a minute later.
Loach came to the rescue again with a fingertip save when Shiels tried to curl the ball home in the 11th minute before Don Cowie relieved the pressure with a shot which was comfortably held by Neil Sullivan.
Doncaster should have been in front as half-time approached but the visitors goal continued to lead a charmed life with Loach tipping a clever shot from Coppinger over the bar before making a splendid save to deny Billy Sharp.
Doncaster made the breakthrough five minutes after the interval when Shiels latched onto a cheeky back-heel from Coppinger and twisted past a defender before rattling home a low shot.
Watford had hardly been in the game as an attacking force but suddenly came out of their shell with Heidar Helguson having a header saved before substitute Will Hoskins went close in the 73rd minute.
Rovers increased their lead seven minutes from time with a screaming 20-yard volley from left-back Gareth Roberts - but Watford battled to the finish with Helguson unlucky to hit the crossbar.
They were rewarded with a consolation goal when Helguson scored from the penalty spot in the third minute of stoppage time after Sam Hird had brought down Hoskins.