Watkin, 23, limped off during Ospreys' 40-19 loss to Racing 92 on Saturday and a scan has revealed cartilage damage.

He will have a meeting with a specialist on Tuesday, 17 December, to decide the next course of action.

Wales open their 2020 Six Nations campaign against Italy on 1 February in Cardiff.

Watkin is expected to miss the Ospreys' Christmas and New Year Pro14 derbies against Cardiff Blues, Dragons and Scarlets with an absence of at least four weeks initially being predicted.

The centre will hope the specialist appointment next week does not result in a longer-term diagnosis.

It will be worrying for Wales coach Wayne Pivac, already without British and Irish Lions Test centre Jonathan Davies for his first Six Nations campaign because of a knee injury.

Watkin partnered Hadleigh Parkes in Wales' midfield as Pivac began his reign with a 43-33 victory over Barbarians in an uncapped match in November.

Cardiff Blues centre Willis Halaholo was in Pivac's first squad but has been ruled out for the rest of the season with a knee injury.

Ospreys centre Scott Williams and Bath midfield man Jamie Roberts are established alternatives Pivac could consider for the Six Nations.

World Cup top try scorer Josh Adams was tried in the centre in the closing minutes against Barbarians, while fellow Cardiff Blues wing Owen Lane has been identified as a long-term midfield option.

Ospreys outside-half Gareth Anscombe has been ruled out of the Six Nations, while Scarlets fly-half Rhys Patchell and Exeter prop Tomas Francis are doubts to take any part in the tournament.

Captain Alun Wyn Jones, James Davies, Aaron Shingler, Liam Williams, George North, Taulupe Faletau, Ellis Jenkins and Josh Navidi are all currently sidelined.

Dragons forward Cory Hill will make his return from a 10-month absence this weekend.