John Kennedy struck a spectacular extra-time winner as Fluminense ended their long wait for a first ever Copa Libertadores crown on Saturday with a 2-1 victory over Argentina's Boca Juniors.

Substitute Kennedy volleyed home from the edge of the area in the 99th minute of an ill-tempered final at Rio's Maracana Stadium after the match finished 1-1 after 90 minutes.

Kennedy was promptly sent off for collecting a second yellow card for an over-exuberant celebration among Fluminense's delirious home fans following the goal.

The 21-year-old Kennedy – named by his history-loving father after the 35th President of the United States – had been a decisive influence for Fluminense after being brought on as a substitute for playmaker Ganso 10 minutes from the end of normal time.

At that point, Boca looked to be getting on top after equalising with a 72nd-minute shot from Peruvian international right back Luis Advincula which cancelled out Fluminense's 36th-minute opener from veteran forward German Cano.

But the arrival of Kennedy breathed fresh life into the Fluminense attack and in the first half of extra-time, the young forward made the breakthrough.

A deft touch by Keno teed up the ball for Kennedy in space, who crashed a thunderous right-foot volley beyond the dive of Boca's former Manchester United and Argentina international goalkeeper Sergio Romero.

Tempers flared near half-time of extra-time with an ugly multi-player melee after unsuccessful Boca appeals for a penalty.

- Cagey 90 minutes -

Boca's Frank Fabra was given his marching orders by Colombian referee Wilmar Roldan after a VAR review caught him aiming a slap at Fluminense defender Nino.

With both teams down to 10 men, Fluminense could have wrapped up victory but Guga's effort after a sweeping counter-attack came back off the inside of the post and rolled across the face of goal.

Fluminense, the four-time champions of Brazil, were one of just two of the country's 12 biggest clubs never to have won the Libertadores prior to Saturday’s victory.

But Kennedy's extra-time thunderbolt handed Fluminense a victory that gives Brazilian clubs a fifth straight win in the tournament since the introduction of single-match format finals in 2019.

The game had gone to extra-time after a cagey 90 minutes finished level at 1-1.

Fluminense had taken the lead with a well-worked opening goal from veteran striker Cano after 36 minutes.

Keno was involved in that goal too, playing a neat 1-2 with Jhon Arias before pulling back for Cano, who swept in an emphatic low finish.

The final looked to be Fluminense's for the taking against a toothless Boca side who had just one shot in the first half.

The second-half began in much the same way, but as Boca began to press for an equaliser, Fluminense dropped deeper and looked increasingly nervous.

They paid the price for that approach on 72 minutes when right back Advincula advanced on goal, cutting in from the flank and unleashing a superb effort into the far corner beyond the dive of Fluminense goalkeeper Fabio.

The goal silenced the Maracana as Fluminense's fans feared the worst against the Argentine giants.

But Kennedy's arrival wrested momentum back in favour of the Rio club, setting up his extra-time winner.