Veteran Japan lock Luke Thompson admitted Friday that the lure of a fourth World Cup was behind his shock call-up to the Sunwolves, but said he would take one game at a time in the hope his Super Rugby form would warrant national selection.

"My first priority is the Sunwolves," he said at the team hotel in Singapore. "I'm here to do a good job and see if I can play and then make myself available (for Japan)."

Thompson, who has played 63 tests for Japan, was back in New Zealand on his deer farm in January following his 13th season with Kintetsu Liners when longtime friend and Sunwolves head coach Tony Brown asked him if he would be interested in one last hurrah.

Having "retired" from international rugby in 2015, Thompson was recalled to the national team in 2017 to face Ireland in Tokyo. Initially calling the appearance a one-off, Thompson changed his tune to "never say never" following a defensive performance that won plaudits from both fans and peers.

He said he received further encouragement a year later while watching Japan play Italy on television.

"My wife saw how animated I was and asked 'Do you still want to do it?' And I thought to myself, 'Maybe.' Thought about it more and realized I do," he said.

(Photo taken in October 2015 shows Luke Thompson holding onto the ball during the first half of Japan's 26-5 win over Samoa in a Rugby World Cup pool match in Milton Keynes, England.)

With Japan's supply of locks in recent years hit by injury and a lack of real world-class competitors, Thompson's re-emergence on the international scene has delighted Japanese rugby fans, who have followed his career since he arrived in 2004.

"It's been a long time since I have won a first cap and I'm looking forward to the whole experience," Thompson said of Saturday's game against the Sharks in Singapore.

When reminded that he would -- at 37 years and 306 days -- be the oldest player to make his debut in Super Rugby, Thompson, who spent two seasons playing for Sanyo (now Panasonic) Wild Knights before moving down to Osaka, laughed and said, "Age is just a number."

"I've been managed very well by Kintetsu in terms of training and game time," he said, during an interview in which he switched with ease between English and the Kansai dialect of Japanese spoken in the Osaka area.

"And getting the balance right in life is so important -- when to turn the rugby on and off."

Thompson admitted he was still playing catch-up in terms of being ready for the extended campaign of a Super Rugby season, but hoped his experience would hold him in good stead.

Asked what he would bring to the Sunwolves, he answered with a Japanese term. "Doryoku," he said, using a word meaning endeavor, ability and effort. "And hopefully a calming influence."