For the briefest moment, Australian star Michael Matthews found himself leading the famed Paris-Nice race - but then the great Tadej Pogacar decided to take over.

Canberra's Matthews had his moment on the road from Saint-Amand-Montrond to La Loge des Gardes on Wednesday, speeding to victory in the final intermediate sprint to pick up key bonus seconds and actually become the virtual overall leader in the celebrated 'Race to the Sun'.

But within minutes, as the fourth stage hit its final 6.8km uphill denouement, the Pogacar super show began as the two-time Tour de France champion carved out a fabulous victory and laid down a significant marker against his big rival, current Tour champion Jonas Vingegaard.

So blistering was the showdown on the first WorldTour summit finish of the European season that Team JaycoAlUla's Matthews, not in the same league as a climber on the average seven per cent gradients, quickly decided to cut his losses and ended up nearly 11 minutes behind.

But Matthews, known throughout cycling as 'Bling', was still in the mix for the race's glittering prizes, lying third in the points competition behind Denmark's Mads Pedersen and the inevitable Pogacar.

Slovenian Pogacar reckoned afterwards that he hadn't expected to take the lead at this stage of the race but shrugged: "You don't say no to yellow, and it's nice to be back."

Not that he's ever been away. Still, it was evident that the world's top-ranked road racer was keen to make a point against Vingegaard, the Dane who succeeded him as Tour champ.

After Vingegaard attacked with just over 4km to the line, Pogacar closed the gap, and when France's David Gaudu then tried to break away himself with 2.5km left, the Slovenian chased him down too.

But Jumbo-Visma's Vingegaard couldn't respond with Pogacar going on to power away from Gaudu in the final metres while the Dane finished 43 seconds behind the winner.

The result took Pogacar to the top of the GC standings, with Gaudu 10 seconds behind, Vingegaard 44 seconds down and Simon Yates, leader of Australian team Jayco AlUla, 56 seconds adrift in fourth.

"I'm a little bit surprised," said Pogacar, when asked about Vingegaard's struggle. "In the end it was really tough and he just missed a little bit to catch me and cracked a little bit."

Leading Australian in the race is now 20th-placed Jack Haig, the Bahrain-Victorious leader, who lost 1:38 on Pogacar while missing out on the 100th top-10 finish of his career, ending up 17th on the day.

In Europe's other big stage race this week, Italy's Tirreno-Adriatico, Belgium's Jasper Philipsen sprinted to the third-stage triumph at Foligno, while Filippo Ganna maintained his overall lead of 28 seconds.

The top Perth duo of Jai Hindley and Ben O'Connor are 15th at 51 seconds down and 16th at 52, respectively, in the standings.