Leach was asked if last weekend's 10-7 win at USC was the high point of his coaching career at Washington State so far. He said the high point is always the next game on the schedule.
"The bigger question is, 'Are we focused on Southern Utah right now?'" Leach said.
Washington State hosts the lower-division Thunderbirds in the Cougars' home opener Saturday.
Many Cougars fans are still reveling, however, in what was just Washington State's ninth win over USC. Southern Cal holds a 58-9 lead in the overall series.
Leach is feeling pretty good about his team.
"The biggest thing is we've finished games," Leach said. "We haven't let things upset our composure."
The Cougars opened the season with a one-touchdown loss at Auburn then upset the heavily favored Trojans despite failing to score an offensive touchdown.
Leach acknowledged it has been an impressive start to his second season at WSU.
"There may be teams ranked ahead of Southern Cal and Auburn, but there are not two teams more physical than those two," Leach said. "Has anybody played more physical teams back-to-back?"
He was flooded with congratulatory phone calls and texts from friends and supporters across the country after the USC win.
Coming off a 3-9 season, the Cougars are showing plenty of confidence, especially at USC.
"It was an intense, tightly fought game," Leach said. "Everything was by a fraction of an inch. It was a body punch game."
The Cougars didn't have the composure to win many such games last season, Leach said.
Last year, their only Pac-12 win was in the season finale against archrival Washington.
This year, "we know what it feels like to win," said cornerback Damante Horton, who was named the Pac-12 defensive player of the week for his two key interceptions against Southern Cal, including one he returned 70 yards for WSU's only touchdown.
"We've got a little swagger," Horton said.
Defensive lineman Ioane Gauta said the Cougars consider themselves the nation's best defense after holding USC to 193 total yards.
"That's how we played on Saturday," he said. "We're very prideful right now."
Washington State will be favored to win its next two games, at home against Southern Utah and Idaho. Their next big test should come when they host No. 5 Stanford during Washington State's annual game in Seattle.