TORREON, Mexico -- Aron Winter was left to wonder what might have been.
Toronto FC crumbled in the second half, conceding four goals as Santos Laguna romped to a 6-2 win on the night and 7-3 on aggregate to advance to the CONCACAF Champions League final against defending champion Monterrey.
"We have given away the game," said Winter, the Toronto manager.
Toronto started brightly at Estadio Corona on Wednesday and led the second leg 2-1 as the first half neared an end. The second goal by Joao Plata had Winter and his assistants celebrating on the sideline.
But the Mexicans scored an injury-time equalizer and then racked up three goals in 10 minutes in the second half before adding another stoppage time score as defensive mistakes cost Toronto dearly.
"The crucial moment was the second goal before halftime and the third goal," said Winter.
But the Toronto FC manager lamented conceding "four easy goals."
Santos also showed its teeth at home in the quarter-final against the Seattle Sounders, pouring in four second-half goals to win 6-1 on the day and 7-3 on aggregate.
Plata scored both goals for Toronto.
In the other semi, Monterrey tied at Pumas 1-1 and moved into the final 4-1 on aggregate.
Santos Laguna's Juan Pablo Rodriguez converted penalties in the 56th and 64th minutes with insurance goals from Oribe Peralta in the 66th and David Luduena in second-half injury time.
Herculez Gomez had two in the first half for Santos, both times on floated balls that landed just behind the defence.
The teams tied 1-1 last Wednesday in a stormy game at BMO Field that saw two Santos players sent off and a near brawl at the final whistle after Toronto fullback Ashtone Morgan was head-butted.
Peralta drove at the Canadian goal after a good through ball in the second minute but a Canadian defender forced him to pause and his shot deflected wide off a leg.
Nick Soolsma found Luis Silva unmarked in front of goal in the fourth minute but the rookie was unable to keep his header down.
Santos striker Christian Suarez drove a shot from just outside the box right at Milos Kocic in the 10th minute.
The Santos defence was found wanting several times early and Toronto went ahead in the 15th minute on a header by Plata. A Soolsma corner dropped to an unmarked Silva, whose close-range shot was cleared off the line by a Santos defender. But the ball went straight to the five-foot-two Plata who nodded it in.
Several other Santos attacks were negated by close offside calls in the first half. At the other end, Soolsma was a constant threat down the right side.
Gomez tied it up in the 31st minute after a long floated ball found him inside the Toronto defence, with defender Miguel Aceval a step behind. The U.S. international whipped a low right-footed shot past Kocic, who didn't have a chance, from just inside the box.
The goal came after Toronto lost possession on its own throw-in.
Peralta came close in the 42nd minute when he deflected a hard cross over the bar.
Toronto scored seconds after when the ensuing goal kick went to Soolsma who flicked it on to Plata and the pint-sized Ecuadorian's right-footed shot from the edge of the box beat Oswaldo Sanchez in the 43rd.
Santos tied it up in first-half injury time when a long ball found Gomez a step ahead of Ty Harden this time. The American's right-footer shot found the corner as a close offside decision finally went the way of the Mexicans.
Gomez had a glorious chance at his hat trick in the 54th when a free kick at the side of the box found him all alone. But his shot squibbed wide.
Julian de Guzman triggered the first penalty when he took down Suarez at the edge of the box on the right side. Toronto argued the call but Honduras referee Jose Pineda was unmoved.
Rodriguez fired a high shot down the middle of the goal in the 56th minute and Toronto assistant coach Bob De Klerk was subsequently ejected for jawing at the officials.
Aceval gave away another spot kick when he handled the ball while trying to dive to head away an Ivan Estrada cross from close range near the byline. Rodriguez slammed home another high shot in the 64th.
"I don't know if it was really a 100 per cent penalty, but I think it was given too quickly," said Winter.
The bottom fell out for Toronto two minutes later when Peralta flicked home a shot after the ball found its way to him in the box from a short corner. Luduena added to the pain when he curled home a shot in second-half injury time.
With Santos holding an away goal, Toronto had to win or play to a higher-scoring tie to advance to the final of the club championship for North and Central America and the Caribbean. Another 1-1 tie would have forced extra time and possibly penalties.
The lone MLS side in the final four, Toronto has already made Canadian soccer history by advancing this far.
Despite a quarter-final win over the defending MLS champion Los Angeles Galaxy, Toronto is now a combined 1-4-2 in league and CONCACAF Champions League play this season. On the MLS front, Winter's club is 0-3-0 and has not scored in 208 minutes.
Santos (9-2-2) leads the Mexican standings and is unbeaten in seven games at home this season. A 3-1 win over Toluca on Sunday extended its league win streak to five games.
Toronto was without big striker Danny Koevermans, who picked up a second yellow last week, while Eric Avila and Logan Emory are cup-tied.
Santos' Carlos Darwin Quintero and Osmar Mares missed the game in the wake of last week's red cards.
Torreon is located in central Mexico, some 800 kilometres northwest of Mexico City. Its population is more than 600,000.
Pumas, down 3-0 after the first leg, hosted defending champion and fellow Mexican side Monterrey in the other semifinal Wednesday.