BASEL, Switzerland — Young forward Dimitri Oberlin used a special occasion to inspire Basel to a stunning 5-0 win over Benfica in the Champions League on Wednesday.

On his 20th birthday, the Cameroon-born Oberlin scored twice, had one assist and also earned a penalty as Basel defied a lackluster start to the season.

Benfica played with 10 men for the last half hour after midfielder Andre Almeida was sent off for jumping into a two-footed tackle that appeared vengeful when losing the ball.

Still, the Benfica defense had already been shredded by slick Basel counterattacks. The visitors were shambolic when substitute Blas Riveros completed the scoring in the 76th minute, seconds after Basel hit each post with back-to-back shots.

Basel is second in Group A behind Manchester United, which won 4-1 at CSKA Moscow to follow its 3-0 home win over the Swiss two weeks ago.

Oberlin set the tone as the driving force for two first-half goals that finished end-to-end moves he started from Basel’s penalty area.

In the second minute, Oberlin surged in two different phases of an attack that saw him draw goalkeeper Julio Cesar out of position and tee up defender Michael Lang to fire in a low shot.

Basel’s second goal in the 20th started when Oberlin headed clear Benfica’s corner from his own goalmouth and took off sprinting upfield. He collected Renato Steffen’s pass near the Benfica area and slipped a shot past Julio Cesar, Brazil’s ‘keeper at the 2014 World Cup.

It was quite a start for the Switzerland youth international making his first Champions League start on loan from Austrian title-holder Salzburg.

Oberlin was fouled for the penalty kick that Ricky van Wolfswinkel converted in the 60th, and again scored easily past Julio Cesar in the 69th after slack Benfica passing in defense.

Basel’s new management team began the game under pressure from a poor start to the season for the eight-time defending Swiss champion.

Though losing at Man United was no surprise, Basel languishes in fourth place in its home league.

Television cameras caught sporting director Marco Streller — a former Basel forward appointed this year by the club’s new ownership — reacting with evident relief to the early lead. Coach Raphael Wicky, in his first season of senior management at any club, punched the air wildly at each goal.