Youssef Chermiti took the match ball after a three-goal performance. A multi-million pound signing, openly derided and much-maligned. Yet, in the two biggest games of Rangers' season, he's been the hero.

Youssef Chermiti cost the Ibrox club a fee of around £8m in the summer, having not scored a goal in two years. His name was attached to criticism of former sporting director Kevin Thelwell, with his unconvincing early performances only adding fuel to the fire of his doubters.

Yet, against Celtic in the new year's derby, he came good. His two goals shot Rangers to a 3-1 win at Celtic Park, leading to Wilfried Nancy being sacked and pushing Danny Rohl's side past Celtic in the Scottish Premiership table for the first time this season.

On Sunday, he started in the biggest game of the season so far against league leaders Hearts. Trailing by five points, a win was a must. Thanks to Chermiti, that's what they got. With the weight of the world on his shoulders, the Portuguese striker scored a first ever career hat-trick and heaved a chunk of momentum back behind Rangers in the title charge.

Watch: Rangers v Hearts - Sportscene highlights.

The strangest thing about all this - Chermiti has scored just seven league goals this season. Five of them in two games. Two big games, right enough, but two games all the same. Interestingly enough, he is actually outperforming his xG of just 5.21, despite some notable misses. The 21-year-old ranks just 15th in the league's strikers in that metric.

When you look at his touches in the opposition box - 60 in total - he ranks down in 26th. In 15 league games, 10 of which were starts, he went goalless. Before the 4-2 win over Hearts, he had drawn a blank in his past six games. For all that, his impact in big games is immeasurable.

Yet, pundit Michael Stewart remains unconvinced. "He scored a hat-trick today, which is wonderful for him, but his all-round game is a little bit slack, and his touch at times is very unpredictable," said Stewart on Sportscene.

The opinion that really matters, though, is that of his gaffer and Rohl is clearly a big fan. "You give him belief and trust," the head coach said through the week, when asked about his striker. "You can imagine for Youssef, it's tough for him. Not about the reaction [from fans], it's more about how he feels.

"He knows he wants to score. He wants a lot for the group. He comes in a good situation. I wish that the next time he takes an extra touch and then he looks for the corner, he makes it.

"It will come, I totally believe, because I see a lot of things in him. "It was the Celtic game when he scored, he turned the game with fantastic goals, and he can do this again. I believe, totally." Not a bad prediction from the 36-year-old, who has masterminded Rangers' resurgent form.

Podcast: Dramatic Sunday in Premiership as Celtic & Rangers narrow gap on leaders Hearts.

In Rohl's first weekend as Rangers boss, they leapt from eighth to fifth thanks to a 3-1 win over Kilmarnock, which featured Chermiti's first goal for the Ibrox club. They were 13 points behind Hearts before a ball was kicked. Yet now, with 11 games of this rollercoaster season left, Rangers are just two behind Derek McInnes' pacesetters. It's a turnaround that few could have predicted, and many Rangers fans had already effectively written the league off.

In 19 league matches in charge, Rohl has won 14, drawn four and lost just one - to Hearts at Tynecastle Park back in December. "It's not been pretty for Rangers for the most of this season," former Rangers midfielder Scott Arfield said on BBC Radio Scotland's Sportsound. "Danny Rohl has gone in there and quietly got this team firing again."

The importance of the new head coach cannot be understated, and even caught the eye of Scotland boss Steve Clarke. "He's found a way of playing that suits the squad of players that he's got," Clarke said on Sky Sports. "He showed midweek [against Motherwell] that he's not afraid to make changes, so he trusts his squad.

"When you win matches you get more confidence. If you come in as a manager and start by winning games, immediately the players are going to be onside. The players are with him, the crowd are with him as well. It's been a really good run for Rangers and they're certainly doing very well at the moment."

Chermiti hat-trick earns Rangers seismic win over leaders Hearts. Visit our Rangers page for all the latest news, analysis and fan views. Get Rangers news notifications in the BBC Sport app.