One bad inning derailed LSU’s season.

Houston scored seven runs in the bottom of the third inning Monday night, then rode it and the arm of relief pitcher Jared Robinson to a 12-2 rout of LSU in the championship game of the NCAA Tournament’s Baton Rouge Regional.

Houston (48-16) advanced to its first super regional since 2003. It’ll play Texas in a best-of-three series beginning Friday.

LSU (46-16-1), the Southeastern Conference tournament champion and the No. 8 national seed, lost two straight games to Houston in its home park after ripping off 10 wins in a row.

“This game today was not indicative of our season. We won 46 ball games, the SEC tournament championship and we were a national seed. We were 2-0 in this tournament and seemingly in the driver’s seat yesterday,” LSU coach Paul Mainieri said. “Unfortunately we just didn’t get it done when we needed to. When I think of the 2014 season, I’m not going to think about this game. I’m going to think about all the great things that these guys accomplished throughout the season.”

Robinson (5-1) entered to squelch a rally in the third and stymied the Tigers for the better part of the next six innings. He faced 15 straight batters without allowing a hit.

Robinson threw 6 1/3 scoreless innings on Monday, allowing only four hits with a walk and eight strikeouts. He also threw 6 2/3 innings Friday in an opening-round win over Southeastern Louisiana.

“You go out and take it one pitch at a time. You read the hitters the best you can. For LSU, every one of those guys can swing the bat. You have to pitch backwards on occasion to shake them and keep them guessing,” Robinson said. “I tried throwing my off-speed more. Throwing it for a strike threw them off guard. I don’t think they expected it. It gets hitters off guard.”

Each team scored twice in the first inning, then Houston blew it open in the bottom of the third.

A walk, a single and two hit batters loaded the bases and brought in the go-ahead run. Connor Hollis then delivered a two-run double down the right field line, Ashford Fulmer had an RBI single, and Michael Pyeatt a two-run single to make it 8-2. Frankie Ratcliff capped the rally with a sacrifice fly for a 9-2 lead.

Houston added three runs in the eighth to put an exclamation point on the win.