Henk ten Cate's men were far from convincing against the nine-time participants and needed something special to get a result at the Hazza bin Zayed Stadium.
Right on cue, that's precisely what Romarinho delivered.
The Brazilian's well-struck low drive from distance in the 38th minute fizzed along the surface and into the back of the net to hand Al Jazira the advantage.
The goal proved decisive as the Abu Dhabi outfit held on to their slender lead and secured a place in the quarter-finals where they will face AFC Champions League winners Urawa Red Diamonds.
Fernandinho’s blistering left-footed shot put the visitors up 1-0 in the 27th. Luan floated a shot over Lanus goalkeeper Esteban Andrada in the 42nd to double the advantage and cap a Copa that saw him named the best player of the 2017 edition of the South American club competition.
Although Lanus had produced four second-half goals against River Plate in the return leg of the semi-finals, there would be no miracle comeback this time.
Jose Sand converted a penalty in the 72nd to pull back one goal, but the Argentine side were denied a first Copa Libertadores title.
Gremio added their third title to those they won in 1983 and 1995.
Brazil lifted their third Huawei Intercontinental Beach Soccer Cup title on Saturday with a 2-0 win over Portugal in Dubai.
Gilberto Costa’s men – who join Russia as the only other nation to win the competition three times – continue to hold the upper hand over Portugal, having beaten them at the FIFA Beach Soccer World Cup, the BSWW Mundialito and in the Dubai group stage so far this year.
Goals from Bokinha and Filipe Silva did the damage in a hard fought win that extends Brazil’s winning run to almost three years with Portugal’s competition-best second-place finish unlikely to provide much consolation.
Portugal started brightly, with Mao required to be in top form to keep out the likes of Be Martins as the world champions began in strangely subdued fashion.
Having survived one near-miss with a Jordan Santos free-kick, Leo Martins sent another narrowly wide as Portugal continued to threaten, although Elinton Andrade was on hand at the other end to palm away Bruno Xavier’s strike.
There was little the Portugal stopper could do about Bokinha’s opener however, as the Brazilian collected a pass from Lucao before slotting the ball into the bottom right corner.
Portugal responded positively however, Pedro Silva twice going close to an equaliser before Filipe Silva punished the missed chances by firing high into the roof of the net on the turn.
Brazil went into the final period with that two-goal advantage and were eager to take the sting out of the game inside the last 12 minutes.
Be Martins curled a shot wide for Portugal who survived a scare when Filipe Silva rattled the post shortly after as the game began to build to a climax.
Mao had to save smartly late on from Bruno Novo but the three-time winners avoided any late scares en route to another successful title defence ahead of the Copa Libertadores later this month.
Goals: 0-1: Bokinha, min. 7 (2); 0-2: Filipe Silva, min. 2 (2)
Huawei Intercontinental Beach Soccer Cup 2017
16:15 – Mexico 0-3 Paraguay (Seventh-place play-off)
17:30 – Egypt 1-2 UAE (Fifth-place play-off)
18:45 – Russia 2-4 Iran (Third-place play-off)
20:00 – Portugal 0-2 Brazil (Final)
1st Brazil; 2nd Portugal; 3rd Iran; 4th Russia; 5th UAE; 6th Egypt; 7th Paraguay; 8th Mexico
MVP: Rodrigo (BRA)
Best Goalkeeper: Mao (BRA)
Top Scorer: Jordan Santos (POR) (Eight goals)