* Montes injured two minutes after scoring opener in 3-1 win
* Ecuador's Castillo injures knee in clash, could also miss finals (Confirms injury with coach Herrera quotes)
May 31 (Reuters) - Mexico midfielder Luis Montes will miss the World Cup after breaking his leg in Saturday's 3-1 win over fellow qualifiers Ecuador in a warm-up match in Dallas.
Montes had opened the scoring in the 33rd minute but two minutes later he was in agony after challenging for a loose ball with Ecuador's Segundo Castillo.
"It's the tibia and fibula and he'll have to have an operation which won't be at all easy," said Mexico coach Miguel Herrera.
"I feel quite disconcerted because when a player has that impetus and will these things shouldn't happen," he told the post-match news conference.
Team medical officials removed Montes' shin guard after cutting away his sock as he lay in extreme pain. With some of his team mates in tears, Montes was carried off on a stretcher and taken to hospital.
Castillo was also substituted with a knee injury and is also in danger of missing the tournament in Brazil which kicks off on June 12.
Herrera said Villarreal's Javier Aquino was probably the player he will call up to replace Montes in his 23-man squad.
"Aquino is the first option we have in mind, but we're going to anaylse (the situation) well. He's his natural reserve but we'll see," Herrera said.
It is the second player Mexico have lost from their squad for the finals after Juan Carlos Medina withdrew on May 20 with an ankle injury requiring surgery. He was replaced by Miguel Ponce.
"The lads go on to the pitch to give of their best and unfortunately there are these kinds of situations. We ask the players to give their maximum but we have to carry on, there's no turning the page, we have to press on," Herrera said.
Mexico will face hosts Brazil, Croatia and Cameroon in Group A at the World Cup. Ecuador are in Group E with France, Switzerland and Honduras. (Reporting by Simon Evans and Rex Gowar; Editing by Ken Ferris)