Striker Shinji Okazaki scored twice with Yasuyuki Konno and Ryoichi Maeda also on target as Alberto Zaccheroni extended his unbeaten run as Japan coach to 18 games with the victory.

Japan lead Group C with 10 points from four matches in the third round of the Asia zone 2014 World Cup qualifying competition and will take one of the 10 places in the fourth round if Uzbekistan beat North Korea later on Friday.

“The result was the most important thing today. We want to have already qualified for the final stage before we play our last game against Uzbekistan so the win was crucial,” Italian Zaccheroni told reporters.

Having trounced Tajikistan 8-0 in Osaka last month Japan were again expected to steamroller their opponents, ranked 130th by FIFA, but their neat passing game suffered in a difficult first period on the patchy pitch at Dushanbe Central Stadium.

Konno eased the nerves, however, when he converted a rebound in the 36th minute to score his first goal for his country.

Okazaki headed the second just past the hour mark with substitute Maeda firing home from the edge of the area with eight minutes remaining.

VfB Stuttgart striker Okazaki then wrapped up the scoring in stoppage time with his 26th goal for the Blue Samurai.

Japan travel to Pyongyang to play North Korea on Tuesday, while Tajikistan, who cannot qualify for the next phase after their fourth defeat in the group, are away to Uzbekistan.