How it happened
Thyago Ayala was the reason Sarmiento did not lose. The goalkeeper made seven saves and earned a match rating of 8.1 in a 1-1 draw, level with River Plate's Nicolás Otamendi for the highest on the pitch.
Sarmiento took the lead through Contrera in the 15th minute and went into the interval 1-0 ahead. River Plate pressed for the rest of the match and found the equaliser through Montiel in the 71st minute.
That was the only time Ayala was beaten. River Plate put eight shots on target, so seven stopped and one scored is the full account of their threat on goal. No red cards changed the course of the match.
The numbers
River Plate dominated the ball with 73% possession and outshot their hosts 22 to 11. They also won the corner count 9 to 5 and the expected-goals count 1.78 to 1.24, a gap of 0.54.
Sarmiento were not passive in front of goal. They put four of their 11 shots on target, and an expected-goals figure of 1.24 suggests the chance they created was not a one-off.
Ayala touched the ball only 36 times, a goalkeeper's workload in a game his side mostly defended. Otamendi had 94 touches for River Plate, while Ángel Correa, who was rated 8.0, made a key pass and carried an expected-goals figure of 0.40.
What it means
The result extends a run of mixed but productive results for both sides. Sarmiento have won six, drawn two and lost two of their last 10, scoring 17 and conceding 12. River Plate have won five, drawn four and lost one, with 16 scored and 10 conceded.
River Plate's record against Sarmiento is strong, with five wins, three draws and two defeats in 10 meetings, so a draw is a respectable return for the home side. This was a Matchday 11 fixture in Group B of the Clausura.