The countdown to the 2015 Rugby World Cup is now approaching single digits, meaning that excitement levels are continuing to build by the day.

With each team completing their warm-up fixtures over the weekend, and attention now firmly fixed on next week's grand opening, a clearer picture can be built of how each side is shaping up.

Here, Sports Mole picks out five fixtures in particular which could have a huge say in who progresses beyond the group stage and into the knockout rounds.

1. England vs. Wales (Pool A - Match 16, Twickenham)

It goes without saying that each game in Pool A will carry significant weight. Only two of Australia, Wales and England can make it out of the tough-looking group, while Fiji will also provide a stern test. It is this fixture, though, contested between two of world rugby's fiercest rivals, which truly stands out.

England hold the advantage thanks to their Twickenham surroundings, but that has certainly not stopped Wales recording famous victories in the past. The Red Rose did travel to Cardiff earlier this year and show real determination and character to steal an opening-day Six Nations win, which could stand them in good stead heading into this one.

2. Australia vs. Wales (Pool A - Match 35, Twickenham)

Just to emphasise that point about the importance of each fixture in Pool A, it could very well turn out to be a straight battle between Australia and Wales for second place should England live up to their pre-tournament expectation levels.

The Red Dragons will play two of their opening-round matches on home soil at the Millennium Stadium - always a big advantage - but rather ominously this one will be staged in the English capital. Thousands of Wales supporters are expected to make the journey across the Severn Bridge, though, giving this fixture the cutting atmosphere that its star billing truly deserves.

3. France vs. Italy (Pool D - Match 5, Twickenham)

France and Ireland remain the two favourites to battle their way out of Pool D, but an Italy side who have shown signs of improvement will be looking to spoil the party somewhat. Those three European nations could find themselves in their own Tri-Nations series, with Canada and Romania making up the numbers.

Both Ireland and France have indeed lost to Italy in recent times, however, providing a stark warning that they must produce the goods in each fixture if they are to secure a spot in the top two. The reigning Six Nations champs should have more than enough in them, but France will also need to stand up to the plate when it counts the most.

4. Scotland vs. USA (Pool B - Match 18, Elland Road)

It may have been a case of Australia simply looking to roll over their opponents to gain a real confidence booster heading into the World Cup, but the Wallabies certainly took their eye off the prize when allowing the USA to pull back to within four points at 14-0 ahead.

In the end it was a hefty enough defeat for the Eagles, yet if they can summon some of that spirit in this meeting with Scotland, then Pool B is wide open. South Africa will be looking to send out a message, no doubt, while Samoa are likely to offer more of a threat than a Japan side with just the one win to their name in 24 RWC outings.

5. Argentina vs. Tonga (Pool C - Match 27, Leicester City Stadium)

Hardly one for the ages, granted, but there is a real chance for one of these two sides to build some early momentum prior to the knockout rounds. Argentina, boosted by their victory over South Africa in the recent Rugby Championship, join world champions New Zealand as favourites to earn a last-eight spot.

Namibia are ranked lower than any other side in the competition, meanwhile, and you therefore feel that damage limitation could be on the cards. That leaves Tonga and Georgia, themselves ranked at 11 and 16 in the world, to contest with Argentina (eighth) for that second qualification spot. Assuming that New Zealand do not slip up at any stage, of course, it could be a straight shootout.