Outside attacker Max Roquet delivered from the service line in the biggest moments of the match for No. 15 Lewis.
Roquet had back-to-back aces late in the decisive fifth game to help Lewis upset No. 9/8 BYU 25-16, 25-23, 16-25, 11-25, 15-13 on Saturday in Romeoville, Illinois.
The Flyers and Cougars were tied at 12-12 in the final game before Roquet had an ace that landed in front of a diving BYU player. The All-MIVA outside attacker following a timeout from BYU then had another ace to set up a match-point.
Lewis closed out the match on a 6-2 run to earn its first win of the season against a top-10 nationally ranked team. Along with the late-match aces, Roquet had back-to-back kills to jumpstart the run and erase a two-point deficit.
Roquet finished the match with 10 kills and was one of three Flyers with double-digit kills.
Opposite Christian Prayer contributed 14 kills, including having the match-winning kill. In addition, outside attacker Daniel Haber had a match-high 15 kills on a .478 attack percentage.
Despite suffering its first loss of the season, BYU out-hit Lewis .274 to .207 and in the final two games committed a combined two errors. The Cougars also held the Flyers to a combined negative attack percentage in the third and fourth game to rally from a two-game deficit and force a fifth game.
Outside attacker Trent Moser came off the bench midway through the second game and finished with a team-high 14 kills on a .417 attack percentage. Miks Ramanis added 10 kills and hit .364, while middle attacker Gavin Julien had eight kills on a .467 attack percentage.
Julien also had a match-high five blocks, including three blocks as part of a 10-1 run to open the fourth game.
Lewis libero Nico Paula led all players defensively with 13 digs.
This victory for Lewis ends a seven-match losing streak to BYU that dated back to 2014.