Warren Gatland's Wales team plans could be about to change in the next 24 hours

Picking the summer squad this year never seemed like the easiest task, with an out-of-window Test against South Africa before the trip to Australia adding extra logistical hurdles.

There's already seven English-based players not available for that clash on June 22. With the Ospreys playing Munster in the URC play-offs on Friday night, more players could soon be unavailable for that match.

If the Ospreys don't go any further, then Gatland will have 30 players available heading into that clash with the Springboks.

But hopefully that won't be the case. Having defied the odds to get into the play-offs, you wouldn't bet against Toby Booth's side pulling off something similar now they are there.

Starting the play-offs with a trip to Munster isn't easy, but the thing with the Ospreys in recent seasons is, by their own admission, they're a side more suited to cup formats. Give them a one-off match and the power of their pack will always give them a fighting chance.

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Beat Munster and they'll have a semi-final on the weekend of June 15. Win that and you've a final on the same day as the South Africa match. Reach that and all their Wales call-ups are definitely out of contention for Wales' first Test of the summer.

But even if they lost in a semi-final the week before, that doesn't necessarily mean they'd feature at Twickenham.

"That's a decision we'll have to make and see what happens with them," Gatland said. "Hopefully they do go all the way and we'll have to look at bringing some other players in.

"If they win that quarter-final and go onto that semi-final and final we'll have to think who we replace those players with. Fingers crossed they do get that opportunity to go as far as they can."

If the Ospreys' players are unavailable for the South Africa clash, Gatland would have just 24 players in camp ahead of that match at Twickenham.

Some positions have more depth than other, with there being three tightheads and three scrum-halves in the 23. That could change if Henry Thomas' Castres are involved in the Top 14 play-offs, although the French-based prop is understood to be available as things stand.

So unless Gatland fancies having a prop cover the back-row and a nine cover the backline, there'll need to be some call-ups. Although, after Eddie James' call-up, there'd be less cover needed than before.

Going through where Wales could lose Ospreys players, the front-row so far has adequate cover. Even without Gareth Thomas, there's Corey Domachowski and Kemsley Mathias at loosehead, while Elliot Dee and Evan Lloyd provide numbers at hooker if Dewi Lake and Sam Parry are still involved in the play-offs.

Tighthead and lock isn't affected, but back-row is a position which will need a call-up. Without Jac Morgan, there's just three back-rowers in the squad for South Africa - Taine Plumtree, Aaron Wainwright and Mackenzie Martin.

All of those are players who can play predominantly six and eight, highlighting the need for an openside. James Botham seems the next cab off the rank.

Moving into the backs, scrum-half and fly-half aren't necessarily affected, with only the outside backs losing Ospreys players. Owen Watkin's potential absence is now negated by James' call-up, as he joins Ben Thomas and Mason Grady as centres in the squad.

And, in the back-three, Wales are stocked to cope without Keelan GIles. Rio Dyer might be the only other out-and-out wing, but Liam Williams would have no issue playing in the position - having done so on numerous occasions in the past for Wales.

Roberts' call-up on Thursday means there's not necessarily any pressing need for more backline cover, but a back-row would still be required if Morgan isn't about.

That call-up would give Gatland his matchday squad, but there's also the small matter of training. Wales are set to link up officially in the week before the South Africa match, although it's understood players will informally be in camp before that.

And heading into the Springbok clash, the Wales coach will need numbers in training sessions. There's the possibility of Wales training against the U20s regularly, before their own summer campaign, but you could see extra players brought in - even on an unofficial basis - to help out with preparation.

Players currently available for the South Africa match (Ospreys players in italics):

Corey Domachowski, Kemsley Mathias, Gareth Thomas, Elliot Dee, Dewi Lake, Evan Lloyd, Sam Parry, Keiron Assiratti, Harri O’Connor, Henry Thomas, Ben Carter, Cory Hill, Matthew Screech, Mackenzie Martin, Jac Morgan, Taine Plumtree, Aaron Wainwright, Ellis Bevan, Gareth Davies, Kieran Hardy, Sam Costelow, Mason Grady, Ben Thomas, Eddie James, Owen Watkin, Rio Dyer, Keelan Giles, Liam Williams, Jacob Beetham, Cameron Winnett.