When Olivier Giroud plays like this, it would be easy for Arsène Wenger to conclude that he does not need an expensive upgrade at centre-forward. That would appeal to the Arsenal manager's innate sense of financial prudence. It would not, however, appeal to the club's supporters or some of the players, who want to see a statement signing this summer.
Giroud was the big buy last time out, even though at £13m from Montpellier, he has come to feel relatively cheap in terms of the figures being touted for Luis Suárez, Wayne Rooney and Gonzalo Higuaín, Arsenal's three current striker targets. Giroud was generally solid in his debut Premier League season; sometimes outstanding, sometimes frustrating. His 17-goal return was respectable. There is the hope that he could improve this season.
He was outstanding here, as Arsenal created a piece of history by becoming the first Premier League team to play in Vietnam. His first-half hat-trick bristled with the kind of instinctive and ruthless finishing that everybody connected to the club craves. His second was the most eye-catching, thumped into the top corner after an assured first touch and the third was an ice-cool dink over the goalkeeper when one-on-one. Yet the quality of the opposing defence, or the lack of it, had to be considered.
Arsenal overwhelmed Vietnam in the second-half, with Alex Oxlade-Chamberlain sweeping home a fine shot into the far top corner; the young striker Chuba Akpom showing composure for his goals and Ignasi Miquel shooting through a crowd for seven. It was, though, to Vietnam's credit that they continued to fight and Tran Manh Dung's close-range finish sparked wild scenes in the sold-out crowd. Even Wenger said he enjoyed the reaction to the goal.
It was unfortunate that Dong was booked for removing his shirt in the celebrations. There was also a late red card for the home goalkeeper Tran Buu Ngoc, who handled outside his area when confronted by Jack Wilshere, who got his first pre-season action as a 67th-minute substitute.
Wenger had started with a stronger line-up than the eleven he had selected in Jakarta for the 7-0 win over the Indonesia Dream Team against opponents who were the Vietnamese national team in all but name. The game's authorities frown upon club versus country friendlies and so a little semantic wriggling has been required on behalf of the hosts.
The opposition in such pre-season matches must be carefully chosen, balancing the need for them to provide a competitive workout but nothing that might cross any line into the risk of injuries. There was a brief scare when Kieran Gibbs twisted awkwardly on his way down in the first-half and held his lower back but he was able to continue without treatment.
The bottom line is that Arsenal do not want to be losing fixtures early in their preparations. They noted the defeat that David Moyes suffered in Bangkok in his first match in charge of Manchester United and it is not the sort of hiccup they could entertain, however trivial it might appear.
Vietnam were a much tidier team than their Indonesian counterparts and the home crowd got behind them, willing them to inflict some famous damage. But no team at any level can defend like they did.
This was an occasion that will be remembered by the 40,000 crowd, which revelled in Mexican waves and every forward thrust from their team. The Arsenal defence, in which Bacary Sagna started at centre-half, was tested in the first-half.
Giroud made his mark in the early running. He had scored upon his second-half introduction in Jakarta and once again wasted little time, taking a pass from the busy Tomas Rosicky and shooting into the far corner.
Vietnam carried the game to Arsenal in the first half, but Wenger's team had the chances and might have led before Giroud completed his hat-trick just before the interval. Lukas Podolski tricked past two defenders only to pass rather than shoot and he also shuddered the far post after being played in by Rosicky. From the rebound, Oxlade-Chamberlain's shot was cleared off the line.
The second half saw 12 Arsenal substitutions, with Ryo Miyaichi suffering the ignomy of coming on at the interval before departing. The goals came, but not as dramatically as the late monsoon downpour that threatened to sweep all before it. Giroud could claim to have done something similar.
Arsenal (4-2-3-1): Szczesny (Martínez 71); Jenkinson (Olsson 71), Sagna (Aneke 71), Koscielny (Mertesacker h-t), Gibbs (Miquel h-t); Oxlade-Chamberlain (Wilshere 67), Arteta (Ramsey h-t); Gnabry (Walcott h-t), Rosicky (Zelalem h-t), Podolski (Ryo h-t, Eisfeld 71); Giroud (Akpom h-t).