LOS ANGELES -- Jonah Mathews found out as a freshman that nothing is guaranteed at USC. Starting lineups are decided by performances in practice and scrimmages.
The sophomore impressed in the preseason and is keeping it up now that games count.
Mathews scored 18 points, making four of USC's season-high-tying 12 3-pointers, and the 10th-ranked Trojans beat Lehigh 88-63 on Wednesday night for their 21st straight non-conference victory.
Mathews had seven rebounds, two assists and one steal to go with 7 of 10 shooting in his fourth consecutive start. He also guarded Lehigh's best player, Kahron Ross, in the second half.
"Jonah knows what to bring every day," senior Elijah Stewart said. "He knows how to play defense and score."
USC needed rallies from double-digit deficits in its last two wins against North Dakota State and Vanderbilt, but the Mountain Hawks (3-2) provided no such challenge. The Trojans (4-0) led by 18 points in the first half and by 27 in the second.
"Last year they called us the comeback kids," Mathews said. "We can play up or down, but we wanted to make it a smooth game."
Ross led Lehigh with 24 points and Lance Tejada added 19. The Mountain Hawks were held to 36 percent shooting and got outrebounded 49-32.
"Overall, we kind of got looks that we wanted," Ross said. "Some didn't go in but I feel like we kind of got what we wanted. I don't feel like the defense really was that effective. We just missed a lot of shots."
USC put together a 19-6 run over the end of the first half and start of the second, extending its lead to 54-34. Stewart and Mathews each hit 3-pointers as the Trojans scored the first 10 points of the second half.
"It's hard to come back from a deficit like that," Tejada said. "I'm kind of sad, especially for my guys who are from out here because I know how it feels to come to your hometown and not play good. I feel for them."
Boatwright's basket put USC ahead by 23. The Trojans led by that much in the closing minutes on a 3-pointer by Boatwright. With 4:07 to play, USC coach Andy Enfield inserted his bench to finish off the win.
The Trojans opened the game with a 33-15 run that produced their largest first-half lead. They had seven 3-pointers by five players in the spurt, including two each by Stewart and Mathews.
"They contest every shot so you don't really get a lot of open looks," Ross said. "To compete with them you've got to get open shots and get out in transition. I don't think we did that enough."
The Mountain Hawks answered with a 13-2 run -- Ross and Tejada combined for all the points -- to close within seven before USC ended the first half on Boatwright's three-point play for a 44-34 lead.
It wasn't USC's largest margin of victory. That came by 42 points in the season opener against Cal State Fullerton.
Lehigh came in with five players averaging double figures in points, but Ross and Tejada were their only double-digit scorers. Kyle Leufroy of Pasadena shot 1 for 12 from the field and Jordan Cohen from Tarzana was 1 for 4 in their homecoming game. "This is our first big game of the year," Tejada said. "We've got some Cali guys on the team and there were a lot of nerves."
Lehigh's schedule keeps getting tougher, with the Mountain Hawks facing road games at Pitt, Princeton and Virginia before they return home to host Yale on Dec. 6.
USC next faces its toughest opponent so far in No. 16 Texas A&M. The Aggies have wins over then-No. 11 West Virginia and Oklahoma State. The Trojans won 65-63 in College Station last season and they lead the all-time series 2-0. "This is going to be a guard your yard type of game," Stewart said.
Lehigh continues its four-game road trip at Pitt on Saturday.
USC hosts No. 16 Texas A&M on Sunday, its first ranked opponent of the season.
More AP college basketball: http://collegebasketball.ap.org and http://www.twitter.com/AP-Top25
Q&A: Virginia's Tony Bennett on recruiting, transfer rules and a title's impact
Tony Bennett sat down with ESPN to discuss the road ahead for Virginia after winning the national title.
Vanderbilt adds Rice transfer, Croatian forward
Quentin Millora-Brown is transferring to Vanderbilt from Rice. Croatian forward Oton Jankovic signed a national letter of intent.
College basketball transfer rankings for 2019-20 and 2020-21
It's college basketball's version of free agency. We've ranked the top players who are set to switch schools this offseason.