Tottenham’s Son Heung-min scores their first goal. (Source: Reuters)

Son Heung-min sparked Tottenham’s second-half overwhelming of Borussia Dortmund in the Champions League on Wednesday, setting the London club on its way to a 3-0 victory in the last-16 first leg.

After being on the back foot throughout the first half, Tottenham took complete control against the German league leaders once Son netted two minutes after the break to make it four goals in as many games.

Son celebrated with a trademark Tottenham handshake, but went over to Serge Aurier rather than Jan Vertonghen _ the provider of the cross.

“I feel sorry,” Son laughed after the game alongside Vertonghen, “because I didn’t run to him and I ran to the other side.”

Vertonghen got his own chance to celebrate as Tottenham scored two late goals inside three minutes to take a commanding lead to Germany for the return leg on March 5.

Vertonghen raced into the penalty area and arrived at the back post to volley in Aurier’s cross in the 83rd minute.

“Technically he’s just unbelievable,” Son said of Vertonghen, who was playing at left wingback rather than in central defense. “He can play every position. He deserves a goal and an assist.”

With Dortmund struggling, Fernando Llorente scored the third in the 86th when he got a slight touch with his head to turn in Christian Eriksen’s corner.

Both teams were without their top attacking threats as Dortmund captain Marco Reus and Tottenham’s top scorer Harry Kane are injured.

It was a night to forget for United States international Christian Pulisic, who will be playing in London for Chelsea next season, and Jadon Sancho, the 18-year-old former Manchester City attacker who faded in the second half.

“We lost focus,” Sancho said. “Son is a good player but hopefully we can handle him better in the second leg.”

It is the third setback in a week for Dortmund, which was knocked out of the German Cup by Werder Bremen and then drew with Hoffenheim in the league.

“There are periods of a season when things aren’t top, top, top,” Dortmund manager Lucien Favre said. “We need to analyze and work hard to avoid and correct these errors.”

But Dortmund has a five-point lead in the Bundesliga over Bayern Munich, while Tottenham is five points off the pace in the Premier League in third. This is first time the London team has made the knockout phase in Europe’s elite competition in successive seasons. Unlike Dortmund, Tottenham has never lifted the European Cup.

In the night’s other game, Real Madrid scored a later winner to beat Ajax 2-1 in Amsterdam.