Conor McGregor continues to move up the rankings despite being inactive for the best part of a year.After UFC Vegas 17, which was the final UFC event of 2020, McGregor moved up one spot from fifth to fourth, as he swapped with Tony Ferguson. The only fighters ranked ahead of him are Justin Gaethje, Dustin Poirier, and Charles Oliveira.Congrats to the @ufc on a well fought 2020! The only sporting company on the planet to come through the entire year! Incredible!I am honoured to secure their highest PPV of the year with McGregor Vs Cerrone.Congrats Donald, and also on his double submission win last night. #No1 pic.twitter.com/Xvh76Gki3U— Conor McGregor (@TheNotoriousMMA) December 21, 2020It should not be surprising that Ferguson continues to fall down the lightweight rankings given he is on a two-fight skid. In May, he suffered a fifth-round TKO loss to Gaethje, and then at UFC 256, he was dominated by Charles Oliveira.UFC Weight Classes ExplainedROB FONT IS BACK 🔥@RobSFont announces his comeback to the BW division in a HUGE way #UFCVegas17 pic.twitter.com/EmWpxhhfeR— UFC Canada (@UFC_CA) December 20, 2020Other notable movers in the updated rankings is bantamweight Rob Font. The New England Cartel member is now ranked fifth at 135-pounds after moving up six spots following his knockout win over Marlon Moraes. Moraes, on the other hand, dropped fourth spots to seven.Talia Santos also entered the women's flyweight rankings at No. 13 after she defeated Gillian Robertson. The only other notable change was Marcin Tybura becoming the 15th-ranked heavyweight following a TKO win over Greg Hardy on Saturday.When does Conor McGregor fight next?Conor McGregor is set to return to the Octagon in the main event of UFC 257 on January 23 against Dustin Poirier. The event will also take place on Fight Island."When one of us goes to war..." #UFC257 pic.twitter.com/gs3J9mwJfv— UFC (@ufc) December 21, 2020McGregor will be fighting for the first time in over a year, his last fight seeing him TKO Donald Cerrone in 40 seconds at UFC 246. The hope for the Irishman was to fight another time in the summer, and then in the fall, rematch Khabib Nurmagomedov for the belt. However, due to the pandemic, his plans were halted. If McGregor can defeat Poirier again, it is likely he will be fighting for the lightweight title next time out.Also Read: UFC Schedule: When is the Next Fight?Dustin Poirier, meanwhile, returned to the win column last time out with a hard-fought decision win over Dan Hooker. Before that, he was submitted by Nurmagomedov for the undisputed title after he won the interim strap at UFC 236 with another decision win over Max Holloway. Just like McGregor, if Poirier wins, he too will likely be fighting for UFC gold next time out.