Conner Weigman threw two TD passes for the Aggies (5-7, 2-6) and Demani Richardson returned a fumble for a score. The game was tied at 17-all in the third quarter before A&M scored 21 straight points.
“We just weren’t our best today,” Kelly said. “I’d like to give you a reason why weren’t our best but we just weren’t and we needed to be better.”
Kelly said he didn’t think his team overlooked the Aggies.
“We just needed more juice, more fire and we just seemed to lack that today and that’s on me,” Kelly said.
The Aggies, who opened the season ranked No. 6 but won’t qualify for a bowl game for the first time since 2008, had a strong finish to their disappointing season. They won consecutive games for the first time since September after snapping a six-game skid with a victory over UMass last week.
Achane ran for 119 yards and a score before halftime to help A&M to a 17-10 lead.
LSU opened the second half with a nine-play, 71-yard drive, capped by a 19-yard run by John Emery Jr. to tie it at 17-17.
But Edgerrin Cooper hit Jayden Daniels and forced him to fumble on LSU’s next drive. Richardson scooped it up and dashed 37 yards for his second touchdown this season to put A&M on top 24-17 with about seven minutes left in the third quarter.
The Aggies extended the lead to 31-17 on the first play of the fourth quarter when Moose Muhammad reeled in a 21-yard TD catch with one hand.
A 10-yard run by Achane, who returned after missing two games with a foot injury, made it 38-17 with about eight minutes to go.
A rowdy crowd of more than 93,000 fans packed Kyle Field and some began to rush the field with about 17 seconds left, causing a delay. It was a stark difference from last week, when most of the crowd emptied out after halftime on a wet and cold day.
Those fans and several thousand more poured onto the field when time expired.
Daniels threw for 189 yards and ran for 84 more and Emery had three touchdowns for the Tigers, who lost their first game since they fell 40-13 at home to Tennessee on Oct. 8.