Mageean was enveloped in a group of six at the front that gobbled up all six automatic qualifying spots for tomorrow’s semis – though the top 10 all eventually made it through.

After setting a new lifetime best over 1500m of 4:01.21 as part of her mile PB at the Herculis Diamond League meeting in Monaco in July, today’s time of 4:04.18 was very healthy, with no risk of not making the next phase.

The Portaferry athlete was always up among the leading pack, as Australia’s Georgia Griffith set the pace for the first three laps, before falling back to tenth.

Mageean squeezed in between Griffith and Ethiopian Lemlem Hailu to go along with the final surge from the lead group to the line, having over a second-and-a-quarter to spare over those left behind.

Speaking to RTE, Mageean said: “I’m feeling happy to have got through the round. That was the aim.

“Now I need to get home, get recovered and ready for tomorrow.”

The heat was won in 4:03.88 by new 10000m world champion Sifan Hassan of the Netherlands, whose controversial coach Antonio Salazar was found guilty of a myriad of doping offences yesterday, having his accreditation for the Championships revoked – though the American is thought to still be in the host city.

No athlete has ever achieved a 1500-10000m double in history, male or female – though Emil Zatopek did sweep the 5000, 10000 and marathon treble at the 1952 Olympics in Helsinki.

Also progressing automatically as part of Mageean’s group were Faith Kipyegon of Kenya, the USA’s Nikki Hiltz, Winnie Nanyondo of Uganda and Britain’s Sarah McDonald.

Of the other five athletes in the heat, four made it through as fastest losers, including the game Griffith.

Rabaabe Arafi of Morocco (4:08.32) and Jenny Simpson of the United States (4:07.27) won the other heats, with European indoor and outdoor 1500m champion Laura Muir third in Simpson’s race, just edged out in 4:07.37.