Mendoza scored the equaliser in the 58th minute for Chennayin FC after Pune took the lead in the ninth minute through Greek World cupper Kostas Katsouranis.
By virtue of this Chennaiyin FC have managed to keep Pune at bay from top position.
The Chennai outfit is joint top with Atletico de Kolkata at the halfway stage of the tournament with 12 points from seven games, while Pune, who were held to a goalless draw in their tournament opener before being thrashed 0-5 by Mumbai FC in their next game, is lying a close second with 11 points.
Mumbai FC are placed third with 10 points from seven games followed by NorthEast United FC (9 points).
Pune, who made a remarkable comeback in the league after a jittery start, took the lead as early as in the ninth minute through Katsouranis’ spectacular finish.
Israil Gurung sent in a lovely ball from the right wing in front of the keeper, and the defender from Greece stroke the ball with great precision into the goal to send the home crowd into a frenzy at the Shree Shiv Chhatrapati Stadium.
Stunned by the early goal, Chennayin went for the offensive in search of the equaliser and came close when they were awarded a penalty in the 16th minute after Magliocchetti conceded a foul inside the box.
But to the dismay of the visitors, league’s top-scorer and Chennayin’s marque player Elano Blummer missed the golden chance. The Brazilian, who had so far scored eight goals in the ISL, drove the penalty wide of the right pole.
Soon after, the wood work denied Chennayin when Valencia’s fantastic strike hit the right pole.
Valencia was once again at the thick of things as his powerful drive from outside the box was kept out by a full stretched Pune goalkeepeer Arindam Bhattacharjee.
Chennayin FC had the better share of chances in the first half and was once again denied by the wood work when a beautifully taken free kick by Elano hit the cross bar.
Pune had their share of chances as well but Chennayin goakeeper Gennaro Bracigliano made a double save to deny the hosts, who went into the breather with a 1-0 lead.
Chennayin kept up their pressure in the second half with Valencia once again coming close to scoring but his shot from just outside the box sailed inches over the cross bar.
After many attemts on goal, Valencia finally managed to score the equaliser for Chennayin. Balwant provided him with a perfect pass into the box and the striker finished the movecalmly and stylishly to bring the visitors on level terms.
Fast and furious Gurung was then denied by Chennayin keeper Bracigliano, who dived to his right to make a clean save in the 81st minute.