Middlesbrough 0 Manchester United 2:Ryan Giggs and Park Ji-Sung increased Manchester United's stranglehold on the Premier League title as Middlesbrough relegation fears increased.

The Welshman and his South Korean team-mate fired their side to a fifth successive league victory in front of the biggest crowd of the season at the Riverside and established a six point lead over closest rivals Liverpool, who do not play until tomorrow.

Whatever happens at Anfield, United will head into the closing weeks of the season at least three points ahead of the Reds and with a game in hand.

Giggs set the visitors on the road to victory with just his second league goal of the campaign with 25 minutes gone and Park sealed the points six minutes after the restart as United won at a canter.

Perhaps more importantly, they did so without having to call upon the likes of Cristiano Ronaldo, Edwin van der Sar, Michael Carrick, Darren Fletcher and Anderson ahead of Tuesday night’s Champions League semi-final decider at Arsenal.

The Boro faithful among a crowd of 33,767 trailed away from the Riverside knowing their hopes of watching Premier League football next season are receding by the week.

Next Monday evening’s derby trip to fellow strugglers Newcastle is looking increasingly pivotal for both clubs with at least one of them seemingly certain to slip out of the top flight.

The task ahead of Boro was summed up eloquently by a quick glimpse at the team-sheet before kick-off.

Ferguson, with Tuesday night’s visit to the Emirates Stadium in mind, was able to make seven changes — one of them enforced by Rio Ferdinand’s rib injury — without unduly weakening his team.

He was still able to name Patrice Evra, Nemanja Vidic, Paul Scholes, Giggs, Wayne Rooney and Dimitar Berbatov in his starting line-up, while his embarrassment of riches allowed him to keep Ronaldo, Carlos Tevez, Nani and Anderson in reserve on the bench.

By contrast, opposite number Gareth Southgate was forced to field right-back Justin Hoyte on the left with Andrew Taylor injured, and again left misfiring striker Afonso Alves among the substitutes.

Where United exuded experience, particularly in the middle of the park where the economy of movement and accuracy of passing exhibited by Scholes and Giggs was often breathtaking, the Teessiders struggled to break their opponents down.

They caused problems for stand-in keeper Ben Foster with a series of high balls into the box, but otherwise central defenders Vidic and Jonny Evans were largely untroubled.

To their credit, Boro fought and scrapped for every ball, but there was always a feeling that United had several more gears to go through.

Rooney, starting wide on the left, three times went for goal from distance without hitting the target, but Giggs was not so forgiving when he was presented with his chance after 25 minutes.

Federico Macheda, making his first league start for the club, stepped over Vidic’s ball across the edge of the penalty area and the Welshman left keeper Brad Jones rooted to the spot as he drilled to ball into the bottom corner without a second thought.

Boro rallied briefly, but with Berbatov causing problems by launching a series of attacks from inside his own half, they might have been further behind before the break.

Indeed, had Scholes not been uncharacteristically wasteful twice at the death, the game could have been beyond the Teessiders by the time they returned to the dressing room.

The respite was only temporary, however, and although teenager Macheda let the home side off the hook within four minutes of the restart when he fired wide from just six yards after Rooney had left Tony McMahon on his backside, the second goal was just around the corner.

It came with 51 minutes gone when Park swooped on Rooney’s glorious reverse pass to dispatch a venomous shot past the motionless Jones.

United slipped into cruise control as Southgate attempted to freshen things up by sending on Alves and Didier Digard, although it took a brave 65th-minute block by David Wheater to deny substitute Tevez a third goal after Scholes had picked out Giggs with a raking long ball.

Foster was a virtual spectator as the clock ran down with Boro’s fightback never really getting off the ground.

Indeed, United looked more likely to increase their lead with Rooney twice going close late on and Matthew Bates denying John O’Shea his second goal of the week with a fine block nine minutes from time.