Lamela created and scored the opening goal in the 50th minute and started the move that led to the second nine minutes later as River took their tally to four points from two matches in the Clausura championship.
The 18-year-old was at the heart of River's best moves, lighting up a match that seldom rose above the mediocre as both teams attempted to improve poor relegation averages.
Lamela, who has cemented his place in the side in the 2010/11 season after a 2009 debut, twice linked up with burly striker Mariano Pavone for the goals.
Having started the move for the opener, he took a square pass on the left from Pavone and chipped the ball exquisitely over advancing goalkeeper Gaston Monzon for his first goal at River's Monumental stadium and third in 17 matches all told.
Nine minutes later, Lamela found a gap in the defence to pass to Pavone on the right and the striker crossed for Paulo Ferrari, who had made a diagonal run from his right back position, to head home at the left post.
Seven years ago River, who had allowed Messi to slip through their grasp, agreed with the then 12-year-old Lamela's parents to pay him a monthly wage to stay and develop at the club rather than take up an offer to move to Barcelona.
River's arch-rivals Boca Juniors, tipped as title favourites, have three points after a 1-0 away win at Racing Club on Saturday helped them recover from the shock of a 4-1 defeat by Godoy Cruz at home last weekend.
Title holders Estudiantes, who won the Apertura championship in the first half of the season, are one of two teams on as maximum six points after their 1-0 win over Quilmes on Sunday.
Olimpo have also won their two matches while Godoy Cruz can join them with a victory over San Lorenzo on Monday.
Velez Sarsfield, runners-up to Estudiantes in December, were shocked 2-1 at home by modest All Boys, who had two players sent off in the final two minutes for fouls on playmaker Maxi Moralez.
