SOUTHAVEN, Miss. — The Louisiana IceGators stumbled out of the gate to open the SPHL playoffs.

Despite jumping out to a 1-0 lead early in the contest, the Mississippi RiverKings responded by scoring three straight goals en route to a 5-3 win in the first game of the SPHL quarterfinals.

Devin Mantha led the RiverKings with two goals.

Game two of the best-of-three series is set for 7:05 p.m. Thursday in the Cajundome.

“Mississippi ran the show tonight,” IceGators coach Drew Omicioli said. “We shot ourselves in the foot after coming out strong for 10 minutes. After that, they dominated us for remaining 50 minutes. Our power play was good (going two-for-four), but our overall five-on-five game has to get a lot better. If not, we’ll be in trouble (Thursday) night.”

John Daniels gave the IceGators their early lead when he scored off a Matt Robertson assist at the 11:35 mark of the first period.

That goal woke up the RiverKings.

Mississippi tied the game on a Devin Mantha goal at the 12:12 mark of the opening frame. Leo Thomas and Ryan Marcuz assisted on the play. Thirteen seconds later, Tim Boyle put the RiverKings ahead with his goal off assists from Linden Bahm and Matt Harrington. The Mantha-Thomas-Marcuz line gave Mississippi a 3-1 lead when Mantha scored his second goal of the night 66 seconds into the second period.

Zac Frischmon cut the IceGators’ deficit to a goal with a power play goal at the 10:25 mark of the middle frame off assists from Blake Hietala and Dan Cornell.

The RiverKings put the IceGators away early in the third period. Richard Coyne and Todd Hosmer each scored in the first 10 minutes of the frame to give the RiverKings a 5-2 lead.

Matt Robertson put the IceGators within two goals of a tie when he scored a power play goal with 5:34 left in the game, but the IceGators couldn’t mount a comeback.

The IceGators will do some soul searching between now and Thursday night’s must-win game at the Frozen Swamp.

“We know we have the ability to win the next two games,” Omicioli said. “We just have to commit to our systems and commit to giving 100-percent effort every shift. Tonight, we took too many shifts off, and it cost us. The beauty of the playoffs is that at the end of the day, it doesn’t matter how you win the games. It matters how many you win. We now need to win two in a row to advance.”