Nicolas Anelka scored a second-half hat-trick as Chelsea came from behind to earn their place in the fifth round of the FA Cup with a 3-1 win over Watford at Vicarage Road.
The move paid off as the striker struck twice in two minutes to put Chelsea 2-1 up after Tamas Priskin had given the hosts a shock lead with a deft chip over Petr Cech.
Jobi McAnuff had a chance to equalise late on for Watford before Anelka turned and shot past Scott Loach in injury time to seal the win.
Samba pounced to level the scores in stoppage time after substitute Keith Treacy's speculative shot had come back off Marshall's chest.
Second-half strikes from Aron Gunnarsson and Michael Doyle had earlier turned the tie on its head after Roque Santa Cruz gave Rovers a second-minute lead.
Gunnarsson equalised just after the hour mark, crashing the ball home from long range after Daniel Fox's cross had been headed to only partial safety.
And with 14 minutes to go Doyle's deflected effort looped over goalkeeper Paul Robinson, but Samba spared Rovers' blushes.
Middlesbrough looked like putting their Premier League concerns behind them against in-form West Ham at Upton Park, but had to settle for a 1-1 draw after conceding a late leveller.
Boro went in front in the 22nd minute when a cross from the right by Gary O'Neil was missed by the Hammers defence and headed in at the far post by Stewart Downing.
But the visitors could not hold on and Herita Ilunga headed Gianfranco Zola's side level just seven minutes from time.
Greg Halford had earlier outjumped Sam Ricketts at the far post to head a seventh-minute opener past Boaz Myhill from David Cotterill's ball.
In the day's lunchtime kick-off at the Liberty Stadium Swansea also drew 1-1 with Fulham, Jason Scotland's fine turn and shot cancelling out Garry Monk's unfortunate own goal which had put the visitors ahead.
The in-form Championship side deserved better than a replay, though, with left-winger Mark Gower firing a shot against the inside of the far post and seeing a golden chance well saved by Mark Schwarzer.