SCOTLAND sit on top of Pool B this morning after a first outing at the Rugby World Cup produced a win of reassuring solidity. Greater discipline in the first half and superior stamina in the second gave them the bonus-point victory, and if this was not quite the complete five-star performance, the five tries and the five points they produced made for a highly satisfactory start to their tournament.

There were flaws, all right, and the relative ease with which Japan regularly broke through the first line of the Scots defence will be a concern. But perfection can wait. This match was about getting any nerves out of the system, withstanding the exuberance of the Japanese play, and continuing the improvement made during the four warm-up games.

Japan began brightly and played a lot of entertaining rugby, but they ran out of steam in a match played just four days after their historic win over South Africa. The fact they were 12-7 behind at the break was an unfair reflection of a first half in which they were marginally the better team, especially in attacking, although those dozen points were all a result of their indiscipline.

They came from four penalties by Greig Laidlaw, who ended up with 20 points in all after converting four of his team’s five tries. Mark Bennett was the outstanding finisher with two of those scores, with the others coming from John Hardie, Tommy Seymour, and, on his 23rd birthday, Finn Russell.

Scotland were 6-0 up after little more than ten minutes as Japan paid for their indiscipline, but Eddie Jones’ team then hit back right after the second score with a lineout drive after a penalty was kicked to touch. A textbook move - simple, predictable but unstoppable - it ended with Amanaki Mafi, the No 8, going over for the first try of the contest. Ayumu Goromaru converted, and Japan found themselves in front.

Mafi - who only came back a few weeks ago after eight months out with a dislocated hip - was the outstanding performer for as long as he stayed on the pitch. But he was carried off injured a few minutes into the second half, and Japan lost a lot of their impetus with him.

Scotland had regained the lead by the break with two more Laidlaw penalties, and they would have been further ahead but for a superb tackle by Goromaru which denied Seymour a try right on half-time. The Japan full-back reduced the deficit with a penalty which was the first score of the second half, but after that his team did not trouble the scoreboard further as Scotland took over.

Hardie was the first try-scorer, plunging over from quick recycling after Stuart Hogg had been downed short of the line. Hogg also did the initial damage for the second with a break through the middle, and this time it was Bennett who profited from speedy continuity to glide through a tiring defence. Laidlaw converted to make it 24-10, and Scotland had some breathing space.

Japan tried to force their way back into the game, but any doubt about the outcome was removed quarter of an hour from time when Seymour intercepted inside his own 22 to run 90m and touch down..Bennett made sure of the bonus point with his side’s fourth try a dozen minutes from time, again proving his ability to slice through the slenderest of openings. Laidlaw’s conversion took the score to 38-10, and the Brave Blossoms, as Japan are known, had wilted at last.

Russell made it five tries with five minutes left, easing over from a five-metre scrum. Another two points from Laidlaw’s boot completed a victory that was far more convincing than all but the most optimistic of Scotland supporters had expected.

Japan ended the match strongly, as if they had remembered too late that they had a reputation as a team who compete for 80 minutes. They could have fallen further behind when Sean Maitland broke from deep, but play was called back.

The Japanese are still in with a shout of qualifying for the quarter-finals, and now have ten days to recover before their next game. Scotland, by contrast, are back in action on Sunday, against the United States in Leeds.

Vern Cotter will freshen up his team for that game, but will be wary of interfering with a successful formula by making too many changes. There could be a first start for Josh Strauss, who made his debut off the bench in the second half, and Maitland, who also came on as a substitute, should be in consideration for a place either at full-back or on the wing.

SCOTLAND 45

Scorers: Tries: Hardie, Bennett 2, Seymour, Russell. Cons: Laidlaw 4. Pens: Laidlaw 4.

JAPAN 10

Scorers: Try: Mafi. Con: Goromaru. Pen: Goromaru.

Scotland: S Hogg (S Maitland 66); T Seymour, M Bennett (P Horne 72), M Scott, S Lamont; F Russell, G Laidlaw; A Dickinson (R Grant 65), R Ford (F Brown 70), W P Nel ( J Welsh 70), G Gilchrist (R Gray 50), J Gray, R Wilson (J Strauss 56), J Hardie, D Denton. Substitute: H Pyrgos.

Japan: A Goromaru; K Matsushima, M Sa’u, Y Tamura, K Fukuoka; H Tatekawa (K Hesketh 73), F Tanaka (A Hiwasa 66); K Inagaki (M Mikami 41), S Horie (T Kizu 72), H Yamashita (K Hatakeyama 53), L Thompson (S Ito 66), J Ives (S Makabe 60), M Leitch, M Broadhurst, A Mafi (H Tui 46).

Referee: J Lacey (Ireland). Attendance: 14,354.