Fukuroi - Japan's Kotaro Matsushima has been likened to a Ferrari, but he admits he'll have to be at full throttle in Saturday's Rugby World Cup clash with Ireland to avoid becoming roadkill.

The flying wing scored a sizzling treble as the host nation beat Russia 30-10 in last week's Pool A opener, prompting gushing praise from Japan coach Jamie Joseph.

But after earning his racing stripes, Matsushima was asked on Friday about chunky Irish wing Jacob Stockdale, who he will come face to face with in Shizuoka.

"If I'm a Ferrari, he's a three-tonne truck - and a fast one," said Japan's hat-trick hero.

"But hopefully I'll see plenty of the ball and can use my speed and have an impact."

Ireland centre Garry Ringrose believes shutting down the prolific Matsushima will be key.

The Irish, who pummelled Scotland 27-3 in their opening game, crushed Japan in back-to-back Tests two years ago, the first at Ecopa stadium, the venue for Saturday's showdown.

"He was incredibly good back then and obviously he's gone from strength to strength," Ringrose said of Matsushima, who has scored nine tries in his last seven Tests.

"Japan are definitely a different beast to what they were two years ago. We're under no illusions how difficult it will be."

Ireland, who have never won a World Cup knockout match, are favourites to top Pool A, but flank Peter O'Mahony insisted they would not underestimate Japan - no longer viewed as tournament whipping boys after humiliating South Africa on England's south coast four years ago.

"It doesn't get any bigger than playing the host nation," he said.

"We're all aware of how dangerous this Japan team is. It's going to take a huge performance from Ireland to beat them."

While Ireland will be without world player of the year Johnny Sexton, Ringrose backed replacement flyhalf Jack Carty to rise to the occasion in only his second Test start.

"Jack is definitely more than ready to play and step up," said Ringrose.

"Obviously adaptability is very important and we've got to be ready to play with different combinations. It's up to the centres - myself and Chris (Farrell) to make his job as easy as possible."

Ireland, likely to face South Africa in the quarter-finals, thrashed Japan 50-22 and 35-13 on their 2017 tour.

They will be expected to prove too strong against in Shizuoka but Ringrose sounded a note of caution, noting how rough-and-tumble those matches had been.

"It was just the tempo they play at but also the physicality they brought," he said.

"After the game there were a few bumps and bruises. But Japan are also very smart in how they play the game."

"As individuals, we won't be able to stop some of the skill and speed they have," added Ringrose.

"We have to be collectively as good as we can be to stop the threats they have."

Teams:

Ireland

15 Rob Kearney, 14 Keith Earls, 13 Garry Ringrose, 12 Chris Farrell, 11 Jacob Stockdale, 10 Jack Carty, 9 Conor Murray, 8 CJ Stander, 7 Josh Van der Flier, 6 Peter O'Mahony, 5 James Ryan, 4 Iain Henderson, 3 Tadhg Furlong, 2 Rory Best (captain), 1 Cian Healy

Substitutes: 16 Sean Cronin, 17 David Kilcoyne, 18 Andrew Porter, 19 Tadgh Beirne, 20 Rhys Ruddock, 21 Luke McGrath, 22 Joey Carbery, 23 Jordan Larmour

Japan

15 Ryohei Yamanaka, 14 Kotaro Matsushima, 13 Timothy Lafaele, 12 Ryoto Nakamura, 11 William Tupou, 10 Yu Tamura, 9 Yutaka Nagare, 8 Amanaki Lelei Mafi, 7 Lappies Labuschagne (captain), 6 Kazuki Himeno, 5 James Moore, 4 Luke Thompson, 3 Koo Ji-won, 2 Shota Horie, 1 Keita Inagaki 

Substitutes: 16 Atsushi Sakate, 17 Isileli Nakajima, 18 Asaeli Ai Valu, 19 Wimpie van der Walt, 20 Michael Leitch, 21 Fumiaki Tanaka, 22 Rikiya Matsuda, 23 Lomano Lava Lemeki