Argentinos Juniors defender Luciano Sanchez was left with a broken leg after an accidental stomp from veteran Fluminense left-back Marcelo during a Copa Libertadores match in Buenos Aires on Tuesday.

Sanchez, 29, suffered the serious injury after Marcelo inadvertently stepped directly on his leg while attempting to make a move with the ball.

The former Real Madrid player was sent off in tears as the Argentine screamed on the pitch, surrounded by concerned players on both teams. The incident took place in the 56th minute of the match, which finished 1-1.

After the game Marcelo posted on social media: "Today, I had to experience a very difficult moment on the pitch. I have inadvertently injured a colleague. I want to wish you the best possible recovery Luciano Sanchez. I send you all the strength in the world!"

Gabriel Avalos opened the scoring with a volley for the hosts in the 14th minute of the first leg of the round-of-16 match. Argentinos later saw its goalkeeper Alexis Martin Arias sent off in the 76th minute, and be replaced by substitute midfielder Luciano Heredia until the end of the match.

Fluminense took advantage of the opportunity and equalized with Samuel Xavier in the 87th minute from long range.

The teams will play again next Tuesday at the Maracana Stadium for a place in the quarterfinals.