(Photo credit: Julia Kapros-Imagn Images)

Theo Corbeanu scored on a first-half penalty kick and Sean Johnson recorded his 108th career shutout to help Toronto FC record a stunning 1-0 victory over host San Diego FC on Wednesday night.

Corbeanu's 20th-minute goal held up as Toronto FC (5-11-6, 21 points) shut down the vaunted offense of San Diego FC. The Reds improved to 3-0-2 against Western Conference foes this season.

Johnson only needed to make one save for his sixth shutout of the season. His career count ranks fourth in MLS history.

San Diego FC (13-7-3, 42 points) remain in first place in the West despite the sluggish setback.

Toronto cautiously protected its late one-goal lead just four nights after allowing Atlanta United to score in the 11th minute of second-half stoppage time for a disappointing 1-1 tie.

Pablo Sisniega made one save for FC San Diego, who fell to 6-3-3 at home.

San Diego controlled the ball for two-thirds of the match and outshot Toronto 7-4 with all its shots coming in the second half. The Reds put two on target to San Diego's one.

High-powered San Diego FC holds the MLS lead with 46 goals.

But the club didn't take a single shot in the first half and didn't place a shot on target until the 71st minute when Chucky Lozano's right-footed shot was stopped by Johnson.

This was San Diego FC's first match since losing high-scoring Milan Iloski earlier this week. Iloski's loan was mutually terminated Tuesday when the two sides couldn't agree to contractual teams. Iloski's 10 goals were second most on the team.

Perhaps another reason for the slow offensive effort