Spurs lie second in Group B, four points clear of Red Star in third, knowing one victory from their final two games will ensure progression to the last 16.
Forward Son, who was left “devastated” by his foul that led to a horrific ankle injury for Everton’s Andre Gomes on Sunday, netted twice in the second half, lashing home a finish from an angle and tapping in from close range.
The South Korean did not celebrate his first goal; instead he clasped his hands and bowed his head.
Mauricio Pochettino’s side went ahead in the first half courtesy of the impressive Giovani Lo Celso, who clipped home a finish on his first start for the club following an almighty goalmouth scramble in which Spurs hit the post and bar. Christian Eriksen added a fourth late on.
Red Star had chances of their own but could not find a way past Paulo Gazzaniga, with the Spurs goalkeeper saving sharply off Milan Pavkov and Rajiv van La Parra.
It was Spurs’ first away win since their thrilling Champions League semi-final comeback against Ajax last season.
Son on song for Spurs
Tottenham’s overall form this season has been poor, losing four of their 11 matches in the Premier League and suffering a 7-2 humiliation at home by Bayern Munich.
But the north Londoners have recovered from that demolition in outstanding fashion, scoring nine goals in back-to-back games against Red Star.
Their victory in Belgrade was all the more impressive as the home side tend to provide a stern examination for the visitors, losing just twice in their previous 21 games in Europe at the Rajko Mitic Stadium, including an impressive victory over eventual winners Liverpool last season.
Son was sent off for tripping Gomes in the 1-1 draw at Goodison Park on Sunday and was visibly distraught by the injury but Pochettino said he was “in a very good way” to play and his two goals showed it.
For the first, he received a pass inside the area from Dele Alli, worked it onto his left foot and smashed a finish into the roof of the net. With the events of Sunday still on his mind, Son opted to remain subdued.
His second finished off a neat team move, converting from close range following Danny Rose’s low cross to the back post.
Midfielder Eriksen came off the bench to round off an excellent night for Spurs by deftly clipping in with five minutes remaining.
Lo Celso displays his potential
Argentine midfielder Lo Celso joined Spurs on loan – with an option to buy – from Real Betis on transfer deadline day in August, but has been restricted to six substitute appearances having struggled with a hip problem.
In Serbia, he showed a glimpse of his potential with an all-round, energetic performance, seemingly shaking of his early season injury issues.
During his 86 minutes on the pitch, Lo Celso touched the ball more times (102) and made more tackles (five) than any other player on the pitch, while he won the ball back eight times. He made 79 passes with an accuracy of 90%.
The former Paris St-Germain player finished off the opening goal well, taking a touch and stroking in from six yards out but not before an incredibly chaotic period of play.
Lo Celso had slipped Harry Kane through on the goal and the skipper toe-poked his effort against the post, while Son saw his follow-up cleared off the goalline.
The Red Star defenders failed to clear and the ball eventually reached Kane again at the back post, but his volley across goal was somehow diverted onto the crossbar by Son from a yard out.
Again Red Star were unable to get the ball to safety, allowing Lo Celso to claim his first goal for Tottenham.
We need to keep going – Pochettino
Tottenham manager Mauricio Pochettino told BT Sport: “We are happy for the performance of the team. It is a very difficult place and we spoke a lot before the game about Liverpool, PSG and Napoli not winning here, but the team was fantastic.
“We controlled the game after we scored and we were much better. We have a big squad and when you have plenty of options you have problems too because someone is happy and someone is not.
“This season is different to the previous season and now we need to keep going. It is only a game and we need to add three more points to qualify but it is a good feeling after Everton.”
Man of the match – Son Heung-min (Tottenham)
Spurs’ scoring run – the stats
- Tottenham’s victory was their first away win in any competition in nine games this season (D5 L3).
- Red Star Belgrade have suffered their heaviest home defeat in their European Cup/Champions League history.
- Tottenham have become the first English team to beat Red Star away from home in a Champions League/European Cup tie.
- Red Star have conceded more goals than any other side after four rounds of matches in this season’s Champions League (13).
- Tottenham have now scored in each of their past 13 Champions League away games – only Chelsea (13 between March 2000 and April 2005) can match such a run among English sides in the competition.
- Giovani Lo Celso scored his sixth goal in his past eight appearances across the Europa League/Champions League.