MANCHESTER, England - Appearing unburdened by the baggage of becoming football's most expensive teenager, Anthony Martial announced himself to Manchester United in the best way possible — with the slickest of debut goals against fierce rival Liverpool.

With his only shot, the 19-year-old striker completed a 3-1 English Premier League win at Old Trafford on Saturday, 20 minutes after coming off the bench in an engrossing second half.

Slaloming through the brittle Liverpool defence in the 86th minute before side-footing home, Martial demonstrated why he is already being compared with France great Thierry Henry.

"I know he has enough pace to dribble but his finishing was fantastic," United manager Louis van Gaal said. "He still has to adapt to a new culture and the high rhythm of the Premier League ... you cannot expect from players at that age that they have consistency."

But if this is a taste of his repertoire of goals, United's decision to pay Monaco up to 80 million euros ($90 million) for the Frenchman will look justified rather than the deadline-day inflated panic buy it appeared this month.

Van Gaal can now reflect on "a difficult period we had in the transfer period with a lot of problems."

"Manchester United is always more worse than the other clubs (but) we have managed it very well," said Van Gaal, who held onto goalkeeper David De Gea and signed a striker as the transfer window closed on Sept. 2.

United is now up to second place — five points behind neighbour City — and Liverpool is ninth with seven points from a possible 15 so far.

Though Liverpool has only three goals this season, Christian Benteke's on Saturday was as spectacular as they come.

The striker netted from an overhead kick to briefly narrow the deficit to 2-1, but Martial's goal two minutes later ensured United did not miss captain Wayne Rooney. A hamstring problem forced the striker out of this meeting of English football's most successful teams who have 38 titles between them.

Martial's moment of flair helped to mask what had been a listless first half between these usually ferocious opponents. In 45 minutes they couldn't produce a single shot on target between them.

That changed four minutes into the second half. What the first half lacked in ingenuity, United made up with a deft set-piece.

Liverpool anticipated Juan Mata whipping a free kick toward goal, but the midfielder rolled the ball to the unmarked Daley Blind, who dispatched the ball into the net with ease from the edge of the area.

It had been a quiet day until that point for De Gea after roars of support from United fans before the game, a day after the goalkeeper unexpectedly signed a new four-year contract following his aborted move to Real Madrid.

De Gea's first meaningful contribution was nearly a costly one: Kicking the ball directly to a Liverpool player before being rescued by his defence. But he then demonstrated why he was so coveted by Madrid by nimbly tipping over a bouncing close-range shot from Danny Ings.

United's scorer became the team's saviour when Blind made goal-line clearances in quick succession: First from Martin Skrtel's header, and then from Roberto Firmino's follow-up at the back post.

The intensity usually witnessed in this rivalry had returned, even though it was missing a single player born in either city in the starting lineups.

United's second goal came after a Spaniard (Herrera) was brought down by a Londoner (Joe Gomez) in the penalty area. Herrera slammed the ball straight down the middle of the net with 20 minutes to go.

It was far from game over for United, and a nervy conclusion looked in store when Benteke produced a moment of supreme athleticism to score in the 84th.

But within two minutes, Liverpool allowed Martial, who had replaced Mata, to cut in from the left flank and produce that moment of debut magic.

"If he talks like that on the pitch that's all we need," United winger Ashley Young said, disclosing Martial's difficulties speaking English. "It was vitally important."