England's Barkley and Costa Rica's Gonzalez fall onto the pitch as Costa Rica's Duarte runs past with the ball during their 2014 World Cup Group D soccer match at the Mineirao stadium in Belo Horizonte
England's Ross Barkley (in white) and Costa Rica's Giancarlo Gonzalez fall onto the pitch as Costa Rica's Oscar Duarte runs past with the ball during their 2014 World Cup Group D soccer match at the Mineirao stadium in Belo Horizonte June 24, 2014. REUTERS/Damir Sagolj

Costa Rica and Greece might have been the underdogs of the World Cup, but that won't stop these teams from proving their worth in the knockout stages of the tournament. On Sunday at 21:00 BST (6:00 a.m Sydney Time), Costa Rica and Greece will duke it out on the pitch for a spot in the quarterfinal round.

What's at Stake?

*Costa Rica shocked the football world by topping a formidable group consists of three former World Cup champions: England, Italy and Uruguay. Now, it's time for coach Jorge Luis Pinto and his guys to prove their awesome performance in the group stages isn't a fluke. For Costa Rica, a victory will catapult them to the quarterfinals for the first time in country's history.

*Greece advanced to the knockout stages for the first time after converting a controversial penalty in the last minute of the do-or-die match with Ivory Coast. With history in the books, the Greeks are looking to set the bar higher as they set their sight on a possible quarterfinal stint on Sunday.

Greece head coach Fernando Santos is very much aware of the capability of the Costa Ricans after they topped what everybody called the Group of Death.

"We have to pay a lot of attention in this game, they came out top in the 'Group of Death'," Greece coach Santos told a press conference via Sky Sports. As a result, we cannot allow ourselves to underestimate them."

Injury Update

Costa Rica: Pinto is expected to field the same 11-man unit that nailed the crucial win over Italy in their second group match. So far, all key players for Costa Rica are still ready to play up to this point of the tournament.

"Costa is expected to name the same XI that beat Italy in their penultimate Group D game, having made two changes to his starting line-up for the 0-0 draw with England last time out," via Sky Sports.

Greece: Greece, meanwhile, could miss midfielder Panagiotis Kone but might re-call captain Kostas Katsouranis, who sat out the match against Ivory Coast after being booked twice.

Predicted Lineup

Costa Rica (Possible, 4-4-1-1): Navas; Gonzalez, Umana, Duarte, Gamboa; Bolanos, Diaz, Tejeda, Borges; Ruiz; Campbell.

Greece Projected Lineup (Possible, 4-3-3) - Karnezis; Torosidis, Sokratis, Manolas, Holebas; Maniatis, Katsouranis, Karagounis (C), Salpingidis; Samaras, Gekas.

Experts Picks

Also Read: Mexico vs. Netherlands Live Stream, Preview, Radio, Live Score & Stats of World Cup Round-of-16

Mark Lawrenson of BBC News believed Costa Rica's flamboyant style will find a way to crack into the Greeks' anti-football approach.

"Greece, for me, still play too much anti-football. I know there is nothing wrong with a team defending and playing on the counter attack but I want Costa Rica to win and I think they will do."

"I played against teams from South or Central America and they would be great on the ball but not so great when it came to the physical side of things. Well this Costa Rica side has got the aggression and the ambition too. They will not lie down," said Lawrenson.