The 22-year-old, born in Nigeria but who runs for Bahrain, has escaped a two-year ban which would have kept her out of the rearranged Tokyo 2020 Olympic Games after a drugs tester knocked on the door of a storage cupboard instead of her apartment.

Naser was charged with four alleged whereabouts failures by the AIU in June.

This included a filing failure on March 16, 2019 and three missed tests on March 12 and April 12 of last year and January 24 of this year.

Missing three tests within 12 months is the equivalent of a doping failure and Naser had been provisionally banned after the charges were brought.

However, the Disciplinary Tribunal has ruled the alleged violation in April 2019 should not stand, which means Naser has not missed three tests inside the 12-month window.

All three of the other charges have been confirmed but Naser is now able to prepare for the Olympics which have been moved to next year because of the COVID-19 pandemic.

Filing failures are backdated to the start of the first quarter - so in Naser's case January 1, 2019.

The AIU can appeal the verdict at the Court of Arbitration for Sport, with the Tribunal acknowledging that awarding the decision in the athlete's favour was "borderline".

When discussing the April case, the Tribunal report claimed the circumstances "would have been comical were the consequences not so serious".

Drug tester Enrique Martinez was looking for Flat 11 in Naser's building and found two doors close to one another.

The left hand door had the number 11 at its side and the right hand door had the number 954 and an intercom, with the number 12 underneath.

This caused confusion as the numbers 11 and 12 actually referred to car parking spaces and were not apartment numbers.

Naser's apartment 11 was behind the right hand door marked 954, and the left hand door marked 11 was in fact a storage unit containing nothing but gas cannisters.

Martinez knocked every five minutes on the storage unit door before the required period of an hour had elapsed, unsurprisingly receiving no response.

He did not use the intercom on the other door, although the Tribunal heard that this did not work anyway.

However, he also did not try to open the second door, which Naser said would have been unlocked as a result of the intercom being broken.

"He should have opened the door to building 954 and knocked on the door of Flat 11 inside the building," the Tribunal report said.

"Had he done that he would have successfully located the athlete at her flat."

Martinez did try to phone Naser, but the Tribunal heard her details were not up to date and there was no number which worked.

Naser had reportedly changed her number several times and had struggled with the ADAMS system which athletes use to enter whereabouts details and other information.

The Tribunal heard she has "never been able to submit her own whereabouts information, let alone successfully log in" and the Bahrain Athletics Association has assigned a member of staff to do so on her behalf.

It was agreed that Naser "did not help herself" in many regards due to the lack of information she had submitted, particularly as she had been warned about missed tests before.

"This was a case very much on the borderline and we hope the athlete will learn from the experience and heed the AIU's warnings," the Tribunal said.

Martinez should not be blamed, the Tribunal ruled, as the door numbering is "extremely confusing".

He had earlier been given a building number which did not exist but found the correct place as he had a picture from a previous visit.

The test was scheduled for between 6am and 7am but Martinez "went beyond the call of duty" and returned later in the day as well, when he failed to find Naser again for the same reason.

He also unsuccessfully tried to find her at Bahrain's National Stadium, an act the Tribunal said went "well beyond his mission".

In clearing Naser, the Tribunal said: "Mr Martinez, quite simply, knocked on the wrong door."

Naser ran the third quickest 400m time in history, 48.14sec, on her way to gold at the Doha World Athletics Championships last year. 

The "wonder time" was the fastest seen since East German Marita Koch set the world record of 47.60 in 1985.

Naser is also a double Asian Games gold medallist and a four-time Asian champion.

In June she had protested her innocence, saying she had "never been a cheat".

To read the full judgement click here.