Semenya, who has elevated levels of male sex hormones, made her move on the last lap, overtaking Kenya’s Beatrice Chepkoech on the final bend and accelerating away to win in 4min 0.71sec.
The 27-year-old’s victory by more than two seconds sliced 1.1sec off Budd’s 1984 South African record and earned Semenya her first Commonwealth medal, to go with her swathe of Olympic and world titles over 800m.
It was a victorious moment for Semenya, who called for assistance for an exhausted rival lying on the track before setting off for a lap of honour wrapped in the national flag.
“I want everyone to know that South African athletes are here to stay. I’m proud to be a South African. We are a great nation and we want to display that to the world,” she said.
But Semenya has long endured scrutiny over her hyperandrogenism and this week, Australian 800m runner Brittany McGowan raised familiar concerns.
“It’s a tough one. It’s tough for a lot of women in the 800m, 400m and 1500m at the moment to compare ourselves and be judged by our governing bodies on those times,” McGowan reportedly said.
Semenya’s emphatic win comes with her future again clouded after the Court of Arbitration for Sport suspended the IAAF’s hyperandrogenism regulations, which now look set to be changed.
However, she is now eyeing the world record in the 800m, in which she will be hot favourite when the heats start on Thursday.
Semenya’s appearance raises new questions at the Games, whose first transgender athlete, New Zealand weightlifter Laurel Hubbard, dramatically injured herself mid-competition on Monday and later said her career may be over.
– Oldest to youngest –
Elsewhere, Botswana’s Isaac Makwala did press-ups on the track after winning the 400m in 44.35sec, Grenada’s Lindon Victor won the decathlon and New Zealand’s Julia Ratcliffe shed tears of joy after she hurled 69.94m to take hammer gold.
Jamaican debutant Ronald Levy outstripped former Olympic bronze-medallist Hansle Parchment to win the 110m hurdles in 13.19, while Kimberly Williams and Shanieka Ricketts formed another Jamaican one-two in the triple jump.
In the pool, Australia rounded off a golden meet with a haul of six victories, while Taylor Ruck, 17, finished with a record-equalling eight medals when she anchored Canada to silver in the women’s 4x100m medley relay.
The oldest competitor in the Games’ history, as well as a girl thought to be the youngest, both drew attention as they took part in shooting and table tennis respectively.
Bob Pitcairn, a 79-year-old former pilot who once foiled the hijacking of a passenger plane, came a respectable eighth of 16 in the Queen’s Prize Pairs finals fullbore shooting.
Just as impressively, 11-year-old Anna Hursey completed her stunning table tennis debut when she bowed out of the women’s singles against Malaysia’s Alice Chang Li Sian.
“Nothing phases her,” said Hursey’s coach Stephen Jenkins, praising the Cardiff schoolgirl’s unflappable nature.
English diving star Tom Daley suffered a setback when he withdrew from the individual 10 metres platform, citing a hip problem following surgery last year.
Daley, the 2010 and 2014 individual winner, who suffered concussion in the build-up to the Games, will still dive in the synchronised platform with his partner Dan Goodfellow.
Australia’s Cameron Meyer won cycling’s men’s time trial ahead of England’s Harry Tanfield and Hamish Bond of New Zealand — a double Olympic rowing gold medallist.
Katrin Garfoot won the women’s time trial and bronze went to England’s Hayley Simmonds, who took up cycling to get in shape and has now ended up with a Commonwealth medal.