Where England vs. Australia will be won and lost

England face Australia in the World Cup quarterfinals on Saturday. ESPN writers Tom Hamilton and Sam Bruce go head-to-head to discuss this weekend's crucial knockout match.

SB: Wallabies fans won't know much about Tom Curry and Sam Underhill, why are they just as good -- or better -- than Michael Hooper and David Pocock?

TH: They started just three Tests alongside each other so will not have the same understanding as the Hooper-Pocock axis, but they are similar in design. Underhill is more a Pocock while Curry is a hybrid between the two. Underhill caused the All Blacks all sorts of trouble last November and also has a habit of putting in remarkable last-ditch tackles as Wales found out a year ago. Curry is just 21 but is a natural at turnovers and also has an eye for the tryline with three in 16 Tests. Eddie calls them the 'kamikaze kids'.

TH: And what about Jordan Petaia? This seems a bit of a bolt from the blue - do you think Michael Cheika has had this up his sleeve for a while?

SB: Cheika said Thursday afternoon that this game hadn't been earmarked for Petaia's move to 13, but I think everyone in Australian rugby has been waiting to see him at outside centre for Australia since his first game for the Reds this season. Petaia was sensational outside Samu Kerevi in the Reds' season opener, against the Highlanders in Dunedin, cruising outside Ben Smith as if the All Blacks star wasn't even in the line and Petaia was only in fourth gear himself. Sadly, injury cruelled his Super Rugby season the following week, but there was just enough in that game - and what he had done in winning the National Rugby Championship Player of the Year in 2018 - to see he had something special. I think his biggest test on Saturday will come in defence; Kerevi has improved his tackling but he remains somewhat of a liability in the midfield and that could have knock-on effects for Petaia, whose two previous international starts have been on the wing. Still, I'm excited to see him at 13 and I think he could give Henry Slade some real issues.

SB: Eddie decision's to move Owen Farrell to No. 10 to me looks like he is worried about Samu Kerevi's ball-carrying threat, and how he could have run over the top of George Ford. But what does it say about the way England want to play the game?

TH: Jones holds England's win over Ireland at the Aviva Stadium close to his heart, and on that day they went with Farrell-Tuilagi-Slade. Had Slade been fit, he may have started more than Ford, but for now, it looks very harsh on Ford who has arguably been England's standout player at this World Cup. Don't for one minute read this as a defensive play, Farrell and Slade will offer a right and left-footed kicking option but they'll look to spread the ball and attack at every opportunity. Tuilagi's match up against Kerevi will be one to keep an eye on, but this is still a surprise call from Jones.

TH: While we're on the subject of No.10s - does Cheika know who his best fly-half is? It seems remarkable the amount of chopping and changing there?

SB: Personally I would have gone for Matt To'omua at No. 10, but you're right in saying the Wallabies have changed their halves like you should your underpants. Firstly, Christian Lealiifano - who starts at fly-half this week -- has done an amazing job in beating leukemia, let along getting back to playing top-class international rugby. Again, Cheika says it's about picking the team that wins this week - I guess what Eddie Jones has done in dropping Ford - but my fear is that Lealiifano will look to go wide early when perhaps the better option is to tuck the ball under his arm and take the line on himself, like Toomua did in terrible conditions against Georgia in Shizuoka. The other issue here is that Will Genia starts at No. 9 and he and Lealiifano only played together against the Pumas in Brisbane earlier this year, so the lack of continuity in their combination is an issue. The key for Lealiifano will be if Genia can take some pressure off him by threatening around the edges; the Wallabies are a much better team when the veteran No. 9 has a run himself.

SB: This is, in my opinion, the Wallabies' best tight-five in some years. Why will England still think they have the upper hand there, particularly at the set-piece?

TH: Joe Marler has arguably been the best loose-head in this World Cup, and he can only make England's bench. England will go hard and early in the front-row, but it was surprising to see Courtney Lawes preferred ahead of George Kruis. Jones maybe feels they can lose a bit of bulk in the second-row to allow Lawes to start but it is testament to the strength in depth England possess that Joe Launchbury cannot make the matchday squad. England should still have the upperhand as their set-piece is strong, and then when Mako Vunipola's race is run, you have Marler to come on.