Mexico are on track to qualify for the quarter-finals of the Olympics after entering the break 0-0 with Switzerland at the Millennium Stadium.
The Central American nation sat top of Group B with four points from two matches prior to kickoff, requiring just a draw to secure progression.
Tottenham Hotspur midfielder Giovani dos Santos was handed his first start of the tournament after recovering from a muscle injury, but couldn't fire Mexico into a half-time advantage as he sent a free kick wide after he was earlier denied by Swiss keeper Diego Benaglio.
Switzerland need to win to have a chance of qualification, but squandered several chances to lead at the break.
Amir Abrashi, Admir Mehmedi and Steven Zuber were all wasteful from good positions early in the period before Innocent Emeghara missed their best chance of the opening 45 minutes in the dying stages of the half.
If they do not break the deadlock in the second period, Switzerland will exit the competition at the group stages.
Joe Fish
