Mara scored his first goal since February 2009 with 1.7 seconds left, and Anaheim beat the slumping Predators 5-4 on Sunday night.
Saku Koivu had two goals, Teemu Selanne added a goal and an assist, and defenseman Lubomir Visnovsky also scored to help the Ducks win their third straight and send the Predators to their fifth consecutive loss. Jonas Hiller made 20 saves on an off night after giving up just two goals in each of his previous six starts.
"We need to play better than that," said Mara, who snapped a 78-game goal drought in the regular season. "We had a lot of mistakes tonight, but we sneaked out a win and that's all that matters. It's a big confidence builder for us to win three in a row. The sign of a good team is finding a way to get a win when you don't play your best."
"Two points is two points. We're not going to lament any other part of it," Ducks coach Randy Carlyle said. "It was one of those games that seemed like we had to work for every inch. Every time we got a lead, they came back."
Corey Perry started the play that led to the winning goal, getting the puck to Bobby Ryan in the left circle before Ryan spotted Mara all alone in the slot. He beat Anders Lindback to the stick side while Nashville's Marcel Goc trailed the play.
"I looked up at the clock and I saw there were 8 or 9 seconds left," Mara said. "Bobby got the puck and I jumped to the net. It was bouncing right there and I just put it into an empty net. It was a great play by those guys. I was just in the right place at the right time."
The Ducks didn't get their first power-play opportunity until Shane O'Brien was sent off for holding Visnovsky with 11:55 left. They took a 4-3 lead exactly 2 minutes later when Koivu redirected Toni Lydman's shot from the top of the left circle past Lindback for his fifth goal of the season and 700th NHL point.
O'Reilly tied it with 3:47 to go, converting Franson's centering pass from the right corner.
"It was a really tough loss," coach Barry Trotz said. "I thought we did a lot of good things. I like the resiliency we showed, but obviously I didn't like the outcome. We kept fighting back, but every time you catch up, they score again. It can be disheartening."
Visnovsky, who spent a good portion of the game jumping into the play when the Ducks had the puck in the Nashville zone, beat Lindback with a screened 25-foot wrist shot from the slot just 49 seconds into the third period for a 3-2 lead after George Parros tried to jam the puck inside the left post.
"They have the green light to go at any time, as long as they go to make it an odd-man rush," Carlyle said of his defensemen. "That is the type of support that we would like to get for our forwards on a consistent basis."
Nashville tied it 3-all when Franson threw the puck toward the net and it deflected off a Ducks player before tricking in off Hiller's pads with 13:45 left.
Koivu, whose multigoal game was the 23rd of his career, gave Anaheim a 2-1 edge at 10:49 of the first on a perfect setup in front by Selanne. But the opportunistic Predators converted a sloppy turnover by Ryan into the tying goal at 17:16.
Hornqvist intercepted Ryan's attempted clearing pass inside the blue line and quickly headmanned it to Sullivan, who sped between Visnovsky and rookie defenseman Cam Fowler and beat Hiller with a short backhander that ended his nine-game goal drought.
"I was just trying to find a place to hide on the bench at that point," Ryan said. "It was an ugly game - certainly not one we want to put in the archives, that's for sure."
Lindback, making his fifth start following a four-game stretch in which Pekka Rinne allowed 16 goals, fell behind 1-0 just 52 seconds after the opening faceoff. Selanne banged home a rebound of Ryan's slap shot from the top of the left circle for his seventh of the season and 613th of his career.
The Ducks' lead lasted less than 2 minutes, as Hornqvist parked himself at the edge of the crease and tipped in O'Reilly's 45-foot wrist shot from the slot after it changed direction off Visnovsky's leg.
Trotz coached his 915th regular-season game, breaking a tie with Montreal's Toe Blake for the fifth-most with one team behind Al Arbour (N.Y. Islanders), Billy Reay (Chicago), Lindy Ruff (Buffalo) and Jack Adams (Detroit).
Trotz, in his 12th season with the Predators, is the only coach they've ever had. The record for most consecutive seasons by an NHL coach at the beginning of a team's history is held by Lester Patrick, who guided the New York Rangers through their first 13 seasons (1926-27 to 1938-39).
Nashville was 0 for 4 on the power play and has scored only twice in 38 opportunities over its last 10 games. ... O'Brien was an eighth-round draft pick by Anaheim in 2003 and played 62 games for them as a rookie before he was traded to Tampa Bay in February 2007 - four months before the Ducks won the Stanley Cup.