Edinburgh - Scotland romped to a record 53-24 victory over 14-man Australia at Murrayfield on Saturday, as a 39th-minute red card for tighthead prop Sekope Kepu led to an eight-try thrashing.
Australia's ill-discipline proved costly again, after the Wallabies had captain Michael Hooper and fullback Kurtley Beale yellow-carded in the 30-6 loss to England at Twickenham last week, while head coach Michael Cheika was subjected to a World Rugby investigation because of his reaction.
This time Cheika could have had no complaints when Kepu was sent off by French referee Pascal Gauzere after clearly smashing a forearm flush into the face of Scotland flank Hamish Watson at a ruck.
Australia were 12-10 ahead at the time but with 14 men they conceded six tries - making seven in total - before they were reduced to 13 players in the 78th minute and Scotland crossed again.
Townsend's team ended up smashing both their record margin of victory against the Wallabies (previously nine points in a 24-15 victory in 1981) and their highest points tally against the men in green and gold (34 in their controversial 35-34 World Cup quarter-final defeat in 2015).
It was Scotland's best points tally against a Tier-One nation, eclipsing the 38 they put past Ireland in 1997, and the final tally was also the highest aggregate points score in a fixture between the two countries.
Australia scored four tries of their own, two by centre Tevita Kuridrani, but it was another depressing afternoon for Cheika and former skipper Stephen Moore in his last match before retiring.
Scotland lost star fullback Stuart Hogg to a hip injury in the pre-match warm-up but still managed to back up both their 24-19 win against the Wallabies in Sydney in June and their outstanding showing in the 22-17 defeat by New Zealand last week.
Flyhalf Finn Russell kicked them into a 3-0 lead with a 14th-minute penalty and two minutes later winger Byron McGuigan, making his first start as a stand-in for Hogg, took advantage of turnover ball to hack up field and dribble the ball over the line for his first international try.
With Russell's conversion, Scotland found themselves 10-0 to the good but after 33 minutes Kuridrani got on the end of fly-half Bernard Foley's perfectly-judged grubber kick to score his first try. Three minutes later Foley teed up Kuridrani for his second try in three minutes.
Foley missed the conversion and from that two-point lead the visitors proceeded to implode in a costly minute of madness before the interval.
Kepu saw red, then Scotland scrumhalf Ali Price picked up the ball from the back of a maul and jinked over for try that Russell converted to give Scotland a 17-12 half-time lead.
The Wallabies drew level three minutes into the second half, Beale darting between Watson and Russell to score.
Foley's scuffed conversion left the scores tied but Scotland started to make the most of their man advantage, scoring two tries in four minutes.
After 45 minutes, Scotland wing Maitland took advantage of turnover ball, racing up the left touchline to score, before lock Jonny Gray raced over from ten yards out just four minutes later.
Russell converted the latter and Scotland were 29-17 ahead.
Townsend's team had their fifth try in the 55th minute, Russell catching the Australian defence off guard with a tap-penalty and shipping the ball to Russell, who jinked past three defenders to claim his seventh try in only 11 internationals.
On the hour the South African-born McGuigan claimed his second try and - after a 68th-minute try by Australia's replacement lock Lopeti Timani - in the final six minutes there were further Scotland tries from captain John Barclay and hooker Stuart McInally, the latter coming after Beale had been yellow carded for slapping the ball out of play in the in-goal area.