Newell's join Estudiantes at top
Midfielder Leonel Vangioni scored Newell's equaliser in the 65th minute when he struck on the turn after a poor punch by Boca's former Argentina goalkeeper Roberto Abbondanzieri.
Striker Lucas Viatri had put Boca in front nine minutes earlier at their Bombonera stadium following a headed pass from former Newell's midfielder Guillermo Marino that appeared to be helped along by his arm.
Newell's, on seven points from three matches, trail Estudiantes on goal difference after the South American champions drew 2-2 at San Lorenzo on Wednesday. Boca have five points.
Promoted Atletico Tucuman upset Huracan, runners-up in last season's Clausura championship, 2-0 with two goals in the last half hour from striker Juan Pereyra. Huracan have lost their three matches so far.
Clausura champions Velez Sarsfield, who have six points from two matches, can overtake the leading pair if they win at Gimnasia-La Plata on Friday.