World Athletics on Thursday filed an appeal with the Court of Arbitration for Sport against the clearance of Bahrain's Salwa Eid Naser to compete, while US sprinter Christian Coleman appealed his two-year ban.
The Athletics Integrity Unit (AIU) disciplinary tribunal ruled in October that Naser had not committed an anti-doping rule violation (ADRV) in relation to an alleged filing failure and missed tests.
In its appeal to the CAS, World Athletics requested that the AIU decision "be set aside and that it be replaced with a new decision in which Salwa Eid Naser is found to have committed an ADRV and sanctioned with a two-year period of ineligibility".
World 400 metre champion Naser was initially charged with breaking whereabouts rules and provisionally suspended in June, but that was dismissed on a technicality.
Nigerian-born Naser, who improved by one second a season from 2016-19, stunned athletics when she powered to the third-fastest 400m in history to take the world title in Doha last year.
Her time of 48.14 seconds was only behind runs by East German Marita Koch and former Czech runner Jarmila Kratochvilova in the 1980s.
In a separate case, Coleman filed an appeal against World Athletics over a two-year ban handed down by the AIU in October for having "committed an ADRV in relation to an alleged filing failure and missed tests".
Coleman requested that the AIU decision be "set aside and that the sanction be eliminated, or in the alternative, reduced".
Coleman also struck gold in Doha, winning the men's 100m title in a world-leading time for the season of 9.76 seconds.
He was provisionally suspended for three 'whereabouts failures' in June.
World Athletics' Disciplinary Tribunal upheld the charge and banned the 24-year-old American for two years, backdated to May 14, 2020.
Should the ban remain in place, Coleman would miss next year's Olympic Games in Japan, where he would have been among the favourites to win 100m gold.
Coleman, who is also the 60m world record holder, only ran in the 4x100m relay heats in his first Olympic appearance in Rio de Janeiro four years ago. The Athletics Integrity Unit (AIU) charged Coleman for missed tests in January and December 2019, as well as for a "filing failure" last April.
To prove an anti-doping violation, an athlete has to have committed three whereabouts failures within 12 months.
Coleman previously escaped suspension on a technicality ahead of last September's World Championships.