STARKVILLE (AP) — Mississippi State’s Tyler Russell is a nervous wreck no more.

The backup quarterback showed plenty of cool as he tied a school record with four touchdown passes, leading the Bulldogs to one of their best offensive performances in a thorough 49-7 win over Memphis on Saturday night.

Russell’s flashy debut highlighted a special night for the Bulldogs, wiped away any residual worries about Russell — perhaps the school’s most heralded recruit — after a shaky spring game and showed that coach Dan Mullen’s two-quarterback system might be an emerging danger in the Southeastern Conference.

‘‘In the spring game I didn’t do as well as I knew I could do but I was able to get my feet wet and learn a few things,’’ Russell said. ‘‘This boosts my confidence a whole lot. This is what I wanted to do.’’

Russell and starter Chris Relf combined for 372 yards passing against the Tigers and new coach Larry Porter, spurring the Bulldogs to 569 total yards — just 27 shy of the school record. It was the most points for the Bulldogs since 2002 and the most yards since 1994.

‘‘I feel pretty confident with both of them,’’ Mullen said. ‘‘If you look at those two guys, they play well together.’’

Mississippi State sold out a nonconference game for the first time and 56,032 long-suffering fans — the fourth largest crowd in Starkville — saw quite a show from Russell, a former Parade All-American from nearby Meridian.

Russell hit Brandon Heavens for touchdowns of 20 and 27 yards and Chad Bumphis with scoring passes of 57 and 25 yards.

He completed 12 of 13 passes on his four scoring drives for 218 yards and finished 13 of 16 for 256 overall.

Relf quickly got on his coach’s bad side when he opened the game with an interception, but over the next several minutes he showed how far he’s come since an inconsistent 2009 season when he was Tyson Lee’s backup.

‘‘I started to go after him and he said, ’Coach, I’m all right,’’’ Mullen said.

And he was. He hit Leon Berry with a 55-yard touchdown pass on the next drive to open scoring. Relf completed 7 of 9 passes for 116 yards.

He was especially effective on the ground in the option attack. Though he finished with just 32 yards, he helped spring LaDarius Perkins on several long runs with timely pitches and made few obvious mistakes after that first drive.

He played just one series in the second half, leading a drive that was capped by Ballard’s 1-yard dive, before sitting out the rest of the game as Russell gained valuable experience. Russell looked lost in the spring game, but suffered only a moment’s hesitation against Memphis after learning the key to running Mullen’s offense.

‘‘I just get the ball in the playmakers’ hands,’’ Russell said. ‘‘That’s what makes my job easy. I think I only got hit once really.’’

Heavens had five catches for 112 yards, Bumphis had four for 100 and Berry finished with five for 91. Vick Ballard rounded out a fairly balanced night with two rushing touchdowns, including a 51-yarder.

Their performance stole attention from an equally dominant defense. Maurice Langston led the attack with two interceptions and the Bulldogs were 1:39 away from scoring their first shutout since 1999.

They held the Tigers to just 41 yards rushing and 237 overall and really turned up stuffed Memphis in the third quarter, allowing just 13 yards.

‘‘The third quarter was definitely the most pleasing quarter,’’ new Mississippi State defensive coordinator Manny Diaz said. ‘‘We imposed our will on them. It was just a flash of what we want to do. Now we can show our guys that and start to learn how to sustain it for 60 minutes.’’

Porter, a former Tigers tailback who served as LSU’s running backs coach before being hired to replace Tommy West last winter, has a lot of work ahead of him. The Tigers, 2-10 last year, didn’t fair well with either quarterback Cannon Smith or Ryan Williams and finished with just 41 yards rushing.

‘‘Offensively we didn’t play well across the board,’’ Porter said. ‘‘I thought you saw some things from different guys at times, but there was no consistency, continuity and no rhythm, so no one really got into a groove.’’