The Diamond League season of elite athletics meetings will now begin in Gateshead on 23 May after the city in northeast England replaced Rabat.
The meeting in the Moroccan capital has been cancelled because of coronavirus restrictions as the pandemic continues to disrupt the calendar as athletes prepare for the rearranged Tokyo Olympics this year.
It will be the first time Gateshead has hosted a Diamond League meeting since the series, formerly the Golden League, was rebranded in 2010.
In other changes to the 2021 calendar, Rome's Pietro Mennea Golden Gala meeting will relocate to Florence following the confirmation on Wednesday that the Italian capital's Stadio Olimpico will host matches in the football European Championship after the Italian government met UEFA's demand that spectators be allowed to attend.
The meeting in Florence will move from 4 June to 10 June.
In another change, the Bislett Games in Oslo, due to take place in June, will be postponed until 1 July to comply with local coronavirus restrictions.
Diamond League chair Sebastian Coe said organisers were "working hard, in extraordinarily difficult and fast changing circumstances, to deliver events for the athletes rather than cancelling them".
Revised 2021 Diamond League calendar:
23 May - Gateshead (GBR)
28 May - Doha (QAT)
10 June - Florence (ITA)
1 July - Oslo (NOR)
4 July - Stockholm (SWE)
9 July - Monaco (MON)
13 July - London (GBR)
14 August - Shanghai (CHN)
21 August - Eugene (USA)
22 August - Venue to be confirmed (CHN)
26 August - Lausanne (SUI)
28 August - Paris (FRA)
3 September - Brussels (BEL)
8-9 September - Zurich (SUI)