Matt Damon's wife Luciana steals the show in plunging sheer dress during loved-up turn at Venice Film Festival

The Oscar-winning star (46) and wife of 12 years are often considered one of the most rock solid in Hollywood and look happier than ever two years after renewing their wedding vows.

Damon and Barroso were among the guests of honour at the premiere of his latest film Downsizing at the Venice Film Festival, with the mother-of-four taking centre stage in a floor sweeping semi-sheer red gown with a plunging cut-out neckline and her other half went for a classic black tuxedo.

Downsizing is a sci-fi satire focused on the perils of overpopulation and sees Damon and his onscreen wife Kristen Wiig debate whether or not to shrink themselves to one percent of their body to live in a luxurious government-funded complex. Wiig, was also on hand to promote the film, with a new slicked back hairstyle and a glittering Zuhair Murad gown.

The couple famously at a bar in Miami where she was working in 2002 while he was filming Stuck On You in Miami and he's never shied away from gushing over his other half.

"I literally saw her across a crowded room, literally," he previously recalled of their first meeting. "Eight years and four kids later, that's my life. I don't know how else our paths would've crossed if that didn't happen. If all those things didn't happen."

He credits marrying a "civilian" with keeping him and his family grounded and doesn't feed the tabloids with a salacious personal life.

“I got lucky, I fell in love with a civilian," he previously told Esquire. "Not an actress and not a famous actress at that. Because then the attention doesn’t double — it grows exponentially. Because then suddenly everybody wants to be in your bedroom.

“But I don’t really give them anything. If I’m not jumping up and down on a bar, or lighting something on fire, or cheating on my wife, there’s not really any story to tell. They can try to stake me out, but they’re always going to get the same story — middle-aged married guy with four kids. So as long as that narrative doesn’t change too much, there’s no appetite for it."

The Venice Film Festival will span over 10 days and actress Annette Bening is presiding over the jury, which will see a host of stars, including Jennifer Lawrence and her director boyfriend Darren Aronfksy, descend on the Italian city.