Australia’s Caleb Ewan has hailed his maiden grand tour stage win in the Vuelta a Espana as the best moment of his career.

The 21-year-old first-year professional, tackling his debut grand tour, caught some of the more seasoned sprinters off guard when he prevailed in a dash for the line after a 167.5km ride from Rota to Alcala de Guadaira in Wednesday’s fifth stage.

Neither German John Degenkolb (Giant-Alpecin), winner of the Milan-SanRemo and Paris-Roubaix, nor Slovakia’s Peter Sagan (Tinkoff-Saxo), a four-time winner of the Tour de France points classification, could conquer the Orica-GreenEdge youngster.

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Degenkolb and Sagan, both favourites to win the stage, finished second and third respectively.

To put the achievement into perspective, only one of cycling’s current group of top sprinters has won a stage in a grand tour on debut.

Marcel Kittel (Giant-Alpecin) took out stage seven of the 2011 Vuelta when he was 23 – two years Ewan’s senior.

But Andre Greipel (Lotto-Soudal), Mark Cavendish (Etixx-Quick-Step) and Alexander Kristoff (Katusha) did not.

Ewan was set up for his breakthrough success in perfect style by other members of his team in the final 50 metres.

“This is by far the best day of my career,” Ewan said.

“To beat some of the top sprinters in the world, especially riders like Degenkolb or Sagan, on a climbing finish like that, that means a lot to me.”

Ewan, who debuted as a trainee with the team after placing second in the under-23 world championships last year, praised his team for believing in him “100 per cent”.

“Some neo-pros take a while to gain respect of team,” Ewan said.

“But my team, straight from start, from the Tour of Beijing last year, they believed in me 100 per cent and always worked for me.

“It’s been such an honour to not have to prove myself to them.

“They respect me, that’s the main thing for me, and that’s the difference between me and a lot of other neo-pros.”

Ewan’s Orica colleague and fellow Australian Mitch Docker suggested the triumph may be the first of many.

“He’s just brand new at a grand tour and he showed that he is ready for the next step, it’s amazing,” Docker said.

The pair’s teammate Johan Esteban Chaves (20th) started the day in possession of the leader’s red jersey but was relegated to second, albeit by only one second to Team Giant-Alpecin’s Dutch rider Tom Dumoulin (15th).

Thursday’s sixth stage is a 200.3km ride from Cordoba to Sierra de Cazorla.