When Ms Rei Umehara, 30, signed up to take part in Season 5 of The Amazing Race Asia, she chose to do it not with her husband, but with her younger brother, freelance videographer Keiji, 26.

Likewise, Power 98 DJ Jerald Justin Ko, 29, picked his colleague, Power 98 DJ Michael Tan, for his partner on the reality television show instead of his wife.

Both did it for the same reason: to avoid marital problems.

Ms Umehara, who has been married for almost two years, says with a laugh: "I've watched past seasons of The Amazing Race and whenever there is a married couple on the show, they end up having huge fights. If my mother-in-law sees how I would treat my husband on the show, I think there would be marital problems."

The entrepreneur, who manages a human resource consultancy firm, declined to reveal her husband's name or occupation.

Ko says jokingly that he is "going with Mike only because I don't want to divorce my wife so early into my marriage". He has been married for slightly over a year to advertising manager Vion Seng, 29.

Ms Umehara and her brother and Ko and Tan form the two teams from Singapore who will compete in Season 5 of The Amazing Race Asia. The previous four seasons ran from 2006 to 2010.

Filming for the new series will start this week, with the show slated to air in October. The two Singaporean teams are joined by nine teams from Indonesia, Malaysia, the Philippines, Thailand and Vietnam. The winners will get US$100,000 (S$134,000) in cash, as in the previous four seasons.

The new season will be hosted by Asian-American actor Allan Wu. Indonesian movie actress Tara Basro will join as a co-host in selected legs of the race.

The Umehara siblings were born in Singapore to a SingaporeanChinese mother and Japanese father. They have an elder brother.

When asked what they have been doing to prepare for the race, Mr Umehara, who is single, says: "I am running, working out and studying the past seasons of The Amazing Race Asia, but my sister has been going on holidays or business trips with her husband."

To which his sister fires back: "I've been doing Sudoku puzzles."

The Power 98 DJ duo, who have been co-hosts on The Night Drive and now The Power Breakfast Show for the last 31/2 years, say they have been preparing for the race by learning to read maps and driving without the aid of GPS.

But they feel they have an advantage over the other teams because they have been through national service "and all the life lessons learnt then would be useful".

Tan, 33, was a signaller in the army and Ko was a medic instructor.

Tan, who is single, says: "Our strategy is to have fun and let the excitement drive us. It doesn't matter how far we go as the competition is with ourselves, just as long as we don't get kicked out in the first few episodes."

When asked how they would handle arguments on the show, the pair agreed on the spot to a random safeword: pineapple.

"When we quarrel, we'll shout 'pineapple' and we'll get a time-out. We'll give each other space until we have cooled down," says Ko.