Middlesbrough ended a three-match losing run with a dominant victory over rock-bottom Watford at the Riverside.
Viduka scored twice but is out of contract at the end of the season
Mark Viduka slotted in Stuart Downing's header to give Boro the lead.
Watford conjured a leveller through a Damien Francis volley but Boro quickly retook the lead as Chris Riggott deflected in George Boateng's shot.
Ben Foster made a series of fine saves in the second half but Viduka grabbed his double before setting up Fabio Rochemback for Middlesbrough's fourth.
Viduka, who received a standing ovation as he was substituted in the closing minutes, is out of contract at the end of the season but proved his worth against Watford.
Another player staking his claim to Boro boss Gareth Southgate was youngster Adam Johnson, who was promoted to the starting line-up in place of Stuart Parnaby.
Johnson was behind Middlesbrough's opener as he jinked past Watford's Jordan Stewart on the right wing and sailed in a cross to Downing, who was waiting at the far post.
The England international nodded his cross to the feet of Viduka, who slotted the ball home in the fifth minute.
After brilliantly keeping Chelsea at bay until the 90th minute a week ago, Watford tamely allowed themselves to be overrun by Boro.
Foster's superb saves kept out a rampant Boro
Middlesbrough were given too much space but showed their own shortcomings by failing to take advantage of the situation.
Against the run of play, Watford made Boro pay for their sloppy finishing as Francis walloped home the equaliser in the 23rd minute.
The midfielder collected Dan Shittu's headed pass and buried his volley beyond Mark Schwarzer.
Four minutes later, Middlesbrough regained the lead - and again the deft Johnson was at the heart of it. The 19-year-old found Boateng in space and his left-footed shot clipped the heel of Riggott, who claimed the goal.
Middlesbrough were on a roll and were denied a third goal when Foster tipped away Downing's left-footed shot. The Watford keeper showed sharp reflexes again when he punched away a Viduka effort late on.
The home side pressed forward relentlessly after the break and Foster dived left and right to single-handedly snuff out Boro's threat.
He easily dealt with Downing's angled effort before making an impressive sprawling save to deny Ayegbeni Yakubu.
The Nigerian striker had so many opportunities but Watford's dogged defence shut him out as James Chambers cleared his lifted strike before Foster was on hand again to smother another effort.
Watford's tactic was to try to equalise on the break but their final touches were not incisive enough with substitute Tamas Priskin and Steve Kabba's efforts tidied up by Schwarzer.
Inevitably, the goal came at the other end as Viduka twisted and turned past three defenders before rifling the ball into the roof of the net on the 75th minute.
Viduka turned provider four minutes later as he fed the ball to Rochemback, who slipped the ball under Foster for his first goal of the season.
Middlesbrough boss Gareth Southgate:
"We are not quite safe yet. There is still lots to be done but we might have enough now.
"We're not going on our holidays but historically we tend to switch off and we have to change that.
"It was a good performance and we thoroughly deserved our win. Despite giving the goal away we kept going, kept pushing forward and kept looking for more goals."
Watford boss Adrian Boothroyd:
"We bombed and were awful from start to finish. We did not apply ourselves.
"I don't accept it when we don't put a physical shift in and we were off the pace and did not give them a game.
Asked if his players had one eye on next weekend's FA Cup semi with Manchester United he said: "If that's the case I'll play the youth team."
Middlesbrough: Schwarzer, Xavier, Huth, Riggott, Taylor (Parnaby 87), Downing, Boateng, Rochemback, Johnson, Yakubu (Christie 80), Viduka (Lee 89).
Subs Not Used: Jones, Euell.
Goals: Viduka 5, Boateng 27, Viduka 75, Rochemback 79.
Watford: Foster, Chambers, Shittu, DeMerit, Stewart, Smith, Mahon (Priskin 46), Francis, Rinaldi, Henderson (Bouazza 29), Kabba.
Subs Not Used: Bangura, Williams, Doyley.
Goals: Francis 23.
Ref: C Foy (Merseyside).