Everyone loves an underdog, particularly at the World Cup.

For all the dialogue about the favorites to win, a handful of teams flying under the radar could also do some damage.

Though these squads aren't as flashy as some others, if the stars align in their favor, they could sneak into the knockout stages.

Tournament football is a different beast. Teams don't need to play pretty to advance to the next round.

It only takes a good run of form and some tournament magic to create a Cinderella story.

Here are four countries that could make surprise runs in Qatar.

Group E: Japan

Although they may be grouped alongside football juggernauts Spain and Germany, Japan have enough quality to pull off an upset in Group E.

Perhaps one of the most technically gifted sides at the tournament, the Samurai Blue led AFC qualifying with 3.2 goals per match, created the most chances with 61 and kept 12 clean sheets, only conceding 0.3 goals per match.

As seen in a 2-0 win against the United States in September, they are adept at counter-pressing the opponent, winning the ball back quickly and scoring with ease.

With a plethora of attacking talent that includes Daizen Maeda, Kaoru Mitoma, Daichi Kamada and Takefusa Kubo, coupled with a tight defense spearheaded by Maya Yoshida, Japan could prove difficult to beat.

Group F: Canada

Canada will appear at their first World Cup since 1986 after waltzing through CONCACAF qualifying in style.

Their tactical setup is ideal for knockout-round football.

Lining up in either a back three or 4-2-3-1, Canada not only have pace in attack to punish opponents in transition but also have enough physicality and recovery speed in defense to get back quickly when pulled out of position.

Manager John Herdman has instilled a warrior mentality into the squad. This attitude saw Canada lead CONCACAF in goals per match, chances created and shots on target.

Players like Alphonso Davies, Ismaël Koné, Jonathan David and Stephen Eustáquio are among the core group who can give Canada the edge over their groupmates.

It won't be easy for the men in red, but they have the mindset, chemistry and heart to make some noise in Group F and beat the likes of Belgium and Croatia.

Group A: Ecuador

Ecuador aren't the most flamboyant South American side, but their wealth of up-and-coming stars could be enough to see them sneak out of a challenging Group A.

Talents like José Cifuentes, Piero Hincapié and Gonzalo Plata make Ecuador an intriguing team to watch.

La Tri scored 1.5 goals per match, just behind Argentina, on their way to finishing fourth in CONMEBOL World Cup qualifying. They also have a stingy defense, only letting in 19 goals during their run to Qatar.

Tactically, Ecuador set up in a defensively rigid 4-2-3-1.

The formation not only provides defensive stability with two holding midfielders but also allows Ecuador to be quick in transition, scoring goals from direct long balls in behind or through counterattacks.

Though Ecuador have a talented young roster, will that be enough to get past the more experienced squads of the Netherlands and Senegal?

They have the grit and rising stars to do so.

Group G: Serbia

Serbia may be a team people overlook, but their talent makes them hard to ignore.

Finishing first in their group in UEFA World Cup qualifying, the Eagles have numerous world-class players who can get them to the knockout stages.

Setting up in either a 3-5-2 or 3-5-1-1, manager Dragan Stojković has his wingbacks hug the touchline to get them higher up the pitch. With this width, Serbia can spam crosses into the box to overwhelm the opponent's backline.

Filip Kostić is a big reason they can play this way. His ability to whip in crosses saw Serbia complete 7.5 per game during qualifying.

Naturally, a forward line that includes Aleksandar Mitrović and Dušan Vlahović will use height as an advantage in the 18-yard box.

Though Brazil is the favorite to top Group G, Serbia should finish second and potentially have enough firepower to go beyond the round of 16.

Statistics via FotMob.