And it went very badly.
Three Arizona quarterbacks shredded the Houston defense and the Texans' offense failed to mount a single serious scoring threat in a 32-0 loss to the Cardinals.
"Tonight was not a good night of football," O'Brien said. "It all starts with me. I've got to do a better job of coaching this team. ... It's the first preseason game and there's nowhere but up from where we are right now."
Playing the entire first half, Fitzpatrick completed 6 of 14 passes for 55 yards with two interceptions as the Cardinals took a 20-0 lead at the break.
"I think it is important to keep in mind that it's the first time we've been out there as a team," Fitzpatrick said, "but it's also a nice little wake-up call for me and for everybody. The NFL is a humbling game."
Arizona's first-team defense had a three-and-out and an interception in its two series.
"You come out and put up a result like that and everybody does need to do better," the Texans' J.J. Watt said. "... So we go in and watch the film tomorrow, learn from it and hit the practice field. That's what training camp is for, that's what the preseason is for. You get better and you don't accept things like that."
The Texans were penalized 13 times for 126 yards.
"Tonight there were too many penalties, turnovers, couldn't get off the field on third down, couldn't get a kickoff returned past the 15-yard line," O'Brien said. "It was bad football."
Palmer was 5 for 5 for 84 yards and a TD in his lone stint.
Thomas played the entire second half, completing 11 of 12 for 113 yards and a touchdown.
The Texans, coming off a 2-14 season, got inside the Cardinals' 30-yard line once, and that ended with an interception.
Arizona rookie John Brown, a third-round draft pick from little Pittsburg State (Kansas), caught five passes for 87 yards, all in the first half.
Brown said it was a relief going against a defense other than the strong Cardinals' team he goes against in practice.
"The game was kind of easy," he said, "because going against the best every day, it makes it more relaxing out on the field."
The Cardinals had a 407-172 advantage in total yards and 27-9 in first downs.
Palmer's backup Stanton, who hasn't thrown a regular-season pass since 2010, completed 11 of 17 for 152 yards and 5-yard TD pass to Jaron Brown.
Case Keenum, 0-8 as a starter for Houston last season, played the third quarter, going 3 of 5 for 23 yards.
After Arizona took the opening kickoff, Watt beat guard Jonathan Cooper and sacked Palmer for a 7-yard loss at the Cardinals 15. But on third-and-16, Palmer found the speedy rookie John Brown on a 25-yard play. Moments later, he threw to Housler, who ran down the sideline on a 35-yard play yards to the 38.
Later in the first quarter, Fitzpatrick's pass was tipped by linebacker Kevin Minter. It bounced through the arms of linebacker Larry Foote before cornerback Antonio Cromartie, in his first season with Arizona, picked it off.
NOTES: Arizona was without wide receiver Michael Floyd (groin) and wide receiver-kick returner Ted Ginn Jr. (knee). Arians said Floyd will be out 6-10 days, Ginn about three days. ... First overall draft pick Jadeveon Clowney had some problems but did beat basketball player-turned-tight end Darren Fells to stop Stepfan Taylor for a 5-yard loss. ... Arizona's Dave Zastudil pinned Houston on its 3-yard line with a 54-yard punt midway through the second quarter. He led the NFL in punts inside the 20 the past two years. ... Feely is to kick next week when Arizona plays at Minnesota. ... Starting linemen Cooper and Larsen played the entire first half for the Cardinals.