WATCH | Upbeat Kolisi steps up a gear on 'day 17' of recovery

Springbok captain Siya Kolisi has provided a positive update as he recovers from knee surgery.

Kolisi underwent a knee operation in Cape Town late last month, having suffered the injury playing a URC game for the Sharks against Munster in Durban on 22 April.

SA Rugby said two weeks ago that it "would monitor" Kolisi's recovery and rehabilitation in the coming months.

Springbok team doctor Jerome Mampane said was too early to make any reliable forecasts on when Kolisi would return to action.

On Tuesday, the Bok skipper shared a video on Instagram where he exercised on a stationary bike.

In the video, captioned Day 17, Kolisi appears to be in high spirits and he was also not wearing a protective brace.

A post shared by Siya Kolisi (@siyakolisi)

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Kolisi is in a race against time to be fit for the Rugby World Cup in France later this year. The tournament runs from 8 September to 28 October.

The national skipper will almost certainly miss the Boks' start to the Test season when they contest the Rugby Championship.

In a shortened Rugby Championship, South Africa will host Australia (Loftus Versfeld, 8 July) and Argentina (Ellis Park, 29 July) and face New Zealand away from home (Auckland, 15 July).

The Boks will also play a warm-up match against Argentina in Buenos Aires (5 August), before wrapping up their World Cup preparation with games against Wales in Cardiff (19 August) and New Zealand in London (25 August).

At the World Cup, the Boks will feature in Pool B alongside Ireland, Scotland, Tonga and Romania.

South Africa's 33-man squad for the World Cup will be named on 8 August.