Seoul: Team doctors will be as important as the players in Tuesday's World Cup qualifiers in Asia, as squads deal not only with injuries but long-haul flights.
As well as injuries, suspensions and tactics, some mammoth journeys will be a major factor on matchday two of the third round of qualification for the 2014 World Cup. With all 20 nations playing one game at home and one away in the space of four days all over the giant continent, fatigue looms as a major issue.
Australia have the most arduous journey, flying 12,900 kilometers (8,000 miles) from Brisbane to Dammam in the east of Saudi Arabia for a clash of two teams expecting to progress from Group D.
A recurring theme of the ten games last Friday was how top-ranked teams struggled to defeat weaker nations at home. The Socceroos had to come from behind to beat Thailand 2-1 in Brisbane thanks to a late goal from Alex Brosque.
The match in Saudi Arabia will be much tougher and not just because of the travel. The hosts are now coached by Frank Rijkaard formerly boss of Barcelona and Netherlands. The Dutchman led his team to a goalless draw in nearby Oman in the opening game.
Australia captain Lucas Neill played under Rijkaard at Galatasaray in Turkey and is expecting a tough test in the second match of Group D.
"He gets the players relaxed but also extremely confident in themselves, and he's shrewd," Neill said. "He knows how to play the game. He's played it at the top level; he's coached it at the top level. He would see that as a great challenge and a great opportunity to get one over on us."
After failing to qualify for the 2010 World Cup and exiting the 2011 Asian Cup in the first round, Saudi Arabia are desperate to qualify for the tournament in Brazil, but Rijkaard was quick to deflect pressure on to the visitors.
"Australia has the advantage at this stage in our group as they have defeated Thailand but the contest is still open for all the teams," said Rijkaard.
It is the first time for the two teams to meet since Australia joined the AFC in 2006.
In the other match in Group C, Thailand will be aiming to build on its impressive though fruitless performance in Australia, and get a win at home against Oman.
Like Australia, China also recovered from conceding an early goal to come back and defeat Singapore 2-1.
It was a result that did little to build hopes that China can overcome its long record of underachievement in World Cup qualifying, and already put pressure on new coach Jose Antonio Camacho. The former Spain boss takes the team to Amman to face Jordan, one of Asia's most improved teams.
Jordan picked up an impressive 2-0 win at the home of 2007 Asian Cup winners Iraq to ensure that Zico's first game in charge ended in defeat. The fact that Jordan is coached by Adnan Hamad, an Iraqi and former coach of the Iraq national team, added to the pain.
Zico, who is refusing to talk to the media, takes his team to Singapore for a clash in which the losing team will be in serious danger of dropping out of contention.
Of the top-ranked teams, only South Korea were totally convincing, defeating Lebanon 6-0 in Goyang in Group B. All but one of the goals came from the nation's new English Premier League strikers. Park Chu-young celebrated signing for Arsenal with a hat-trick and Sunderland's Ji Dong-won grabbed two.
"We gave the players compliments after the Lebanon game but we need to forget that match," said Korea coach Cho Kwang-rae who is now preparing for a game in Kuwait.
"We got the start we wanted but it is only a good start if we can build on it. We will play at a fast tempo and if we can play the way we want to play, we can get a good result but first we have to adapt to the difference in climate and conditions after a long journey."
Lebanon host the United Arab Emirates in Beirut, where neither team can afford to lose. Emirates coach Srecko Katanec is in danger of losing his job after a 3-2 home defeat against Kuwait, which followed a disappointing Asian Cup in January. Failure to take three points could end the Slovenian's reign.
In Group C, Japan squeezed past North Korea only because of a goal deep in stoppage time from Maya Yoshida. Next the Asian champions travel to Tashkent to take on Uzbekistan, who also won 1-0, in Tajikistan.
North Korea host Tajikistan in Pyongyang in a game that is already crucial, given both teams lost their opener.
"We understood that we didn't have many chances, but it's very disappointing that we didn't take home a point," North Korea striker Jong Tae Se said of the Japan game. "We have to make sure that we defeat Tajikistan."
Iran can seize control of Group E with a win in Qatar after defeating Indonesia 3-0 in Tehran. Qatar picked up a point with a goalless draw in Bahrain, and that could prove critical, as those teams are expected to fight it out for second place.
Bahrain's English coach Peter Taylor takes his team to Indonesia. A crowd of 80,000 is expected in Jakarta, where Indonesia defeated Bahrain in the 2007 Asian Cup, and the pressure is on the visitors who came close to qualifying for the 2006 and 2010 World Cups but are still seeking a first appearance.
The top two teams from each of the five groups of four progress to the final round of qualifying.