Seven minutes in to the match San Antonio very nearly hit the lead as Leo Cruz was able to get clear on a header but he sent his effort just wide.
The Rayados started the match the stronger side as a wide open net allowed Monterrey a clear chance but they were denied as Josue Soto cleared it off the line.
Monterrey continued their relentless attacking play through the opening 20 minutes and it was only Daryl Sattler who was keeping the clean sheet intact.
But that pressure was always going to tell and in the 24th minute the goal finally came as Carlos Acosta made a run through the Scorpions defense, drawing cover, allowing him to pass to a wide open Guillermo Madrigal who hit the ball low, across the face, keeping it away from Sattler and in to the back of the net.
With ten minutes left in the half the Scorpions started to assert control and Billy Forbes could well have had the lead in the 37th minute as his shot looked destined for the back of the net in the top corner, but Juan Ibarra managed to send the ball out for a corner.
That corner lead to back-to-back efforts from the Scorpions that Cruz was able to get a shot away on goal but was denied by the keeper twice.
As the match headed to half-time the Scorpions found their equalizer as Tomasz Zahorski received a clearance, on the edge of the area and rounded a defender before launching the shot that left the keeper with no chance, making it 1-1 at the break,
Nine minutes in to the second half Monterrey had another dangerous chance as a cross nearly caught the Scorpions out but it was cleared by Julius James.
San Antonio responded in the 65th minute and a free-kick allowed the Scorpions a golden opportunity for Soto, but he stepped up and sent his effort over the bar.
With less than 20 minutes to play Humberto Suazo had a free kick of his own just outside the area but was denied as he sent the effort over the bar.
Monterrey should have won the match in stoppage time as Lucas Silva was left free for a header from close range only to be denied by a stunning Sattler save.
As the final whistle blew, the match was set to go to penalties, but Rayados left the field, leaving the fans disappointed, ending the match 1-1.