Defender Craig Waibel's two headed goals, which sandwiched a pair of Kei Kamara strikes, gave Houston (0-0-2) its second road tie in as many CCL games. Seven goals came during the first half of a see-saw match in which Houston led, 2-0 and 3-2, yet trailed, 4-3, at halftime.
Containing the UNAM attackers, especially Dante Lopez, Fernando Morales, and former Chivas USA midfielder Juan Francisco Palencia, proved problematic for Houston, which fielded Bobby Boswell and Eddie Robinson in central defense and Ricardo Clark as holding midfielder. Yet despite leaving midfielder Brad Davis and forward Brian Ching back in Houston, and starting the match with Dwayne DeRosario on the bench, it matched UNAM chance for chance, and relied on keeper Pat Onstad for a pair of crucial saves at critical moments.
The Dynamo also escaped going down a man in the 27th minute when Robinson yanked on Morales' jersey a few yards outside the penalty area and referee Walter Quesada pulled out a yellow card instead of a straight red for denying a clear goalscoring opportunity.
UNAM scored anyway to tie the match, 2-2, when Efrain Juarez latched onto a clearance of a blocked free kick and drilled a low 25-yard shot just inside the post. Pumas had cut a 2-0 Dynamo lead in half eight minutes earlier when Palencia slipped a through ball that Lopez blasted over Onstad into the roof of the net.
Houston went back in front, 3-2, in the 33rd minute on a Kamara penalty kick after Corey Ashe was victim of a clumsy foul by Juarez. Shortly thereafter, Onstad stoned Lopez one-v-one, but Houston's failure to hold the ball in midfield yielded further UNAM opportunities, two of which it converted.
Palencia tied the match yet again with a simple tap-in after UNAM turned the Dynamo's right flank, and in the second minute of stoppage time Pumas took their first lead with their own set-play expertise. Palencia lofted a free kick from the left flank and Dario Veron escaped the marking of Nate Jaqua to nail a header past a helpless Onstad.
Waibel headed home a Brian Mullan cross four minutes into the second half to end the scoring, which he had opened by nodding home Stuart Holden's corner kick less than four minutes into the match. UNAM, stunned at Houston's audacious spirit, fell further behind in the 16th minute when Ashe headed down Geoff Cameron's cross for Kamara to lash first-time off the underside of the crossbar and over the goal line.
After Waibel's second goal, the eighth goal in 50 furious minutes of play, the pace slackened somewhat, yet both teams produced one clear opportunity that could have won the match. Onstad saved smartly from Lopez and, well into stoppage time, substitute DeRosario lashed a fierce shot that UNAM goalie Sergio Bernal acrobatically turned aside.
Pumas (1-0-2) leads Group B with five points. Houston is tied for second with San Francisco FC (0-0-2) of Panama, which plays pointless Salvadoran club CD Luis Angel Firpo (0-2-0) Wednesday. The Dynamo plays its first CCL home game Tuesday against Firpo at Robertson Stadium.