River are promoted to the top flight, where they hold a record 33 title triumphs, at the first attempt after their shock relegation a year ago almost to the day amid scenes of violence from angry fans who caused damage in and outside the Monumental.
The contrast on Saturday could not have been more marked with scenes of jubilation in the packed stadium as River put their relegation nightmare behind them at the end of an exhausting B Nacional championship that went to the wire.
"This is unforgettable," said coach Matias Almeyda, the former Argentina midfielder who was in the team relegated last year and has just completed his first year on the bench.
"In less than a year we put River back where they belong," a tearful Almeyda told reporters on the pitch.
Former France striker Trezeguet, a boyhood fan who joined the club in the January mid-season break determined to help them regain their top-flight status, scored in the 50th and 89th minutes to take his goal tally to 13.
He also missed a penalty five minutes from time.
River won the championship with 73 points from 38 matches, winning 20 and losing five with a 66-28 goal record.
They will be joined in the first division by Quilmes who finished one point behind after winning 2-0 at Guillermo Brown thanks to a double from Uruguayan striker Martin Cauteruccio.
Quilmes, who won their only first division title in 1978, were also relegated last year.
Four-times first division champions Rosario Central and Instituto, the Cordoba club where Mario Kempes and Osvaldo Ardiles began their careers, also went into Saturday's final round of matches with a chance of direct promotion but lost.
Central, beaten 3-2 at Desamparados, and Instituto, upset 3-0 at home by Ferro Carril Oeste, now go into relegation-promotion playoffs against two first division sides for two places in the top flight.