Despite a massive first-half scare in which Liverpool lost their 2-0 first-leg lead, the Reds came back to score three goals, with the help of Villarreal's erratic keeper.
The three-time capped Argentina international was signed by Manchester City in 2016, but never played for the club, and it's easy to see why.
Rulli's ability was already called into question at Anfield when his side were dominated in a 2-0 defeat in a match that saw him struggle to hold onto the ball.
The 29-year-old looked shaky throughout the first leg, but things got worse back in Spain with his side looking to hold onto a stunning comeback after levelling the tie 2-2 on aggregate.
Unfortunately for Villarreal though, Rulli let a Fabinho shot straight at him through his legs, before failing to collect a close-range Luis Diaz header that was heading straight for him.
A wild rush off his goal line then saw Mane round the former Real Sociedad man to end the tie, and talkSPORT host Jason Cundy was far from impressed.
"The goalkeeper, he's a shocker, I'm sorry," Cundy said. "He was at fault for four of the five goals.
"How can you go into a Champions League semi-final with a goalkeeper that isn't good enough to be an understudy in the Championship?
"Honestly, Sam Johnstone, there's a lot of clubs after him, he's out of contract, he's a better goalkeeper than what I saw tonight and what I've seen over the two legs."
England international Johnstone will likely be on the move this summer, having previously been linked to Premier League side Arsenal.
Who knows though, maybe next season he could be at Villarreal.