Iceland's Swedish coach Lars Lagerback brings a wealth of major tournament experience to the home side while, in contrast, Croatia coach Niko Kovac has been thrown in at the deep end after the sacking of Igor Stimac last month.
Lagerback, 65, took Sweden to the finals of five major championships during an 11-year stint, first as assistant and then as head coach.
He also led Nigeria at the 2010 World Cup in South Africa and the Icelandic football faithful will hope he can deliver them to the promised land of a major finals for the first time.
Kovac's coaching history is modest by comparison.
He was only appointed as Croatia's under-21 coach in January before stepping up when Stimac was fired after taking just one point from their final four qualifiers and ending up in the playoffs.
Lagerback has been blessed while leading Iceland because a golden generation of under-21 players has made it into the senior team.
Many of them took part in the European under-21 championship in Denmark in 2011, and the squad is now peppered with players playing for big-name European clubs.
"We'll play our game and, like I've done with Sweden and Nigeria, we'll look at their strengths and possible weaknesses and then prioritise certain things in our game," Lagerback told Reuters in an interview.
"Now with the playoffs it's a little special as you have a home and away match and away goals count double. If we can keep a clean sheet then they have to score twice as many goals as us in the away game.
"I believe in well-organised play in both defence and attack," he added, indicating his Iceland side will be no different from any other team he has managed - organised defensively and very hard-working.
However, so far his team has looked suspect in defence, leaking 15 goals in qualifying to equal bottom side Cyprus with the worst defensive record in Group E.
Luckily, they also tied with top side Switzerland on 17 goals for the best offensive record, and Lagerback will be confident his side can score against Croatia.
Leading the line will be Kolbeinn Sigthorsson of Ajax Amsterdam, who has netted 13 goals in 19 internationals and is a constant threat up front.
On the bench, veteran Eidur Gudjohnsen, currently with Club Bruges, will be hoping for a victorious end to what will be the last major qualifying campaign for the 35-year-old former Barcelona, Chelsea and Monaco striker.
If Iceland succeed, he will almost certainly be part of the squad in Brazil before calling time on his international career.
Defender Birkir Mar Saeversson is suspended for the first leg after picking up a booking in the final qualifier against Norway, but he will be available for the away leg on Tuesday.
Croatia will also miss left back Ivan Strinic in both legs through an abdominal injury and Danijel Pranjic, who has been recalled after a 16-month absence, is likely to deputise unless Kovac decides to reshuffle the back four.
If the coach deploys Pranjic in a five-man midfield, Vedran Corluka or Josip Simunic would fill the left back slot while the towering Mario Mandzukic will probably start as a lone striker with Ivica Olic battling to recover from a calf strain.
"Olic has still not trained but he is getting better and Pranjic will definitely be an asset because he can play in several positions," Kovac told a news conference on Tuesday.
"We are certain about 90 percent of the starting lineup but things might change and no player can take his slot for granted," he said.
Kovac impressed with the under-21s in their Euro 2015 qualifiers, winning the opening four games before he was named the senior team coach, and he acknowledged Iceland would pose a serious threat.
"They are a good team who have several tall players and are hence always likely to create chances from set pieces, even throw-ins," he said.
"They are well organised and experts at winning the second ball so we have to avoid giving away free kicks in dangerous positions. Our primary objective is to score an away goal that would take off the pressure in the return leg," he added.
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