The Sunwolves let an early lead slip through their fingers to remain winless after seven games of the Super Rugby season after a 24-10 defeat to New Zealand's Blues on Saturday.

The Sunwolves took control of the game at Prince Chichibu Memorial Rugby Ground — their fifth in Tokyo this season — when a Yu Tamura penalty and a Timothy Lafaele try put them 10-0 ahead after 20 minutes.

But the Blues, who went into the match with only one win in six games, stopped the Sunwolves in their tracks with four unanswered tries, leaving the home team still searching for its first victory in its third season in the Southern Hemisphere's premier club rugby competition.

"I'm disappointed," said Sunwolves head coach Jamie Joseph. "We put the Blues under a lot of pressure in the first half. We could have been ahead by another try, another seven points. Going into halftime we were really confident.

"We knew the Blues are the type of team that are not going to go away. There is a lot of X-factor among their group and they are going to keep coming. We really handed that game back to the Blues, and that's the disappointing thing."

The Sunwolves won one game and drew one in their debut Super Rugby season in 2016, and improved on that with two wins last year. Joseph set the team the ambitious target of finishing in the top five in its third campaign, but the 48-year-old was quick to play down his words after the Sunwolves' latest defeat.

"I'm the leader of the team, and I have to set high goals so that my players can aspire to be the best against the best teams in the world," he said. "Secondly, it's a great marketing ploy for us to get support for our team, which is what we need.

"The Blues' target would have been to win the competition, given that they've got 11 All Blacks in their team. But then the confidence goes after you lose a couple of games and get a few injuries. That's the nature of Super Rugby. I'm not sure that's such a big thing."

The Sunwolves were handed an early present when Blues lock Patrick Tuipulotu was sin-binned in the third minute for taking out Kotaro Matsushima, and Tamura slotted home the resulting penalty.

Tamura was forced off for a concussion test soon after but replacement Hayden Parker set up the Sunwolves' opening try, bursting through the Blues' defense before handing off the ball to Lafaele to cross the line. Parker added the conversion himself for good measure.

The Blues replied in the 28th minute with a try from winger Jordan Hyland, and Akira Ioane scored the visitors' second when he rampaged through the Sunwolves' defense 10 minutes into the second half.

"Our communication dropped off in the first five minutes of the second half," said Sunwolves captain Yutaka Nagare. "We started missing individual tackles and giving away penalties. But the biggest thing was giving away that try at the start of the second half. We should have stayed in control but instead it knocked our confidence."

Stephen Perofeta kicked the conversion from Ioane's try to put the Blues ahead for the first time, before substitute Dalton Papalii took advantage of some terrible Sunwolves tackling to stretch the visitors' lead five minutes later.

"I thought our defense was really good today," said Joseph. "But we gave penalties away for being over-keen, and individuals missed tackles which led to tries. Tries lead to pressure, so that's why we lost the game, in my view."

Hyland put the game beyond the Sunwolves' reach with another try in the 76th minute, and Blues head coach Tana Umaga could only sympathize with his beaten opponent's plight.

"We're in a similar boat," said the former All Black. "We haven't had great success this season. It's not through a lack of effort, it's just little things that go your way and a bit of luck.

"It is a tough time for both our sides but all you can ask teams is just to give everything that they've got. I'm looking for all-out effort, and if we can get a bit of execution then usually you get the rewards you're looking for. But the effort has to come first."