Argentina captain Lionel Messi has called Julian Alvarez "spectacular" and "extraordinary" after the 22-year-old's double against Croatia helped them into the World Cup final.

Manchester City's Alvarez took his goal tally to four, one behind joint top scorers Messi and Kylian Mbappe.

Argentina, who last won the World Cup in 1986, face France on Sunday.

"Nobody imagined Julian would have the participation and importance he has shown," said Messi.

"The help he has given us has been absolutely spectacular."

Messi, 35, has dominated the headlines in Qatar, with a string of starring performances in what he has confirmed is his fifth and final World Cup.

He has scored five and created three of Argentina's 12 goals - leaving Alvarez's contribution to go a little under the radar.

The young striker was not expected to feature prominently for Argentina this tournament and only made substitute appearances in their shock opening defeat by Saudi Arabia and the win over Mexico, with coach Lionel Scaloni initially preferring Inter Milan's Lautaro Martinez.

Alvarez has started the four matches since, though, culminating in his impressive display in the 3-0 semi-final victory, in which he was brought down for Messi's penalty opener, before scoring the next two goals himself.

"During the whole World Cup, but also on Tuesday, he was extraordinary," added Messi. "He ran everything. He fought for everything - creating chances, fighting. For us, he was the surprising discovery, and he deserves everything that has happened to him because he is a lovely guy."

'Messi - don't run. I'll do it for you'

Manchester City signed Alvarez from River Plate for 17m euros (£14.1m) in January 2022.

He agreed a five-and-a-half-year deal with City, but remained at the Argentine champions on loan until July.

This season, he has made 12 Premier League appearances - mostly from the substitutes' bench - and has scored three goals.

Former Argentina and City defender Pablo Zabaleta told BBC Sport Alvarez's "work-rate is unbelievable".

"He's playing alongside Lionel Messi up front and it seems, from the outside, that he's like: 'Messi - don't run. I'll do it for you,' he added.

"You need a big heart [to do that]. He started at the World Cup on the bench but then [got] one chance and he's been brilliant."

Former England midfielder Jermaine Jenas said: "At such a young age, to come on to this stage and put in that type of performance, in that moment for his country - incredible."

Alvarez's performances in Qatar will leave Manchester City fans excited by what is to come.

He has made it seven goals in eight international. He has become only the second Argentina player to score four goals at a World Cup while aged 22 or under, after Gonzalo Higuain in 2010.

And he also became the youngest player to score more than one goal in a World Cup semi-final since Brazil legend Pele's hat-trick in a 5-2 win over France in 1958.