South Africa's United Rugby Championship play-off challenge is on red alert with the Welsh opposition loaded with internationals who will play the Springboks in three Test matches in July.

It all adds to the theatre of the final round of the league, with so many of the top eight teams positioned to host a home quarter-final.

The Vodacom Bulls and DHL Stormers must win against the Ospreys and Scarlets respectively to have any chance of a home quarter-final and both South African camps this week have acknowledged how difficult it is for teams in the competition to win abroad.

The four Welsh clubs lost eight successive matches in South Africa but, playing at home, and strengthened with current international players, the landscape is decidedly different.

The Welsh squad to tour South Africa was announced in the week and 22 of the 33 names come from the Ospreys, Scarlets and Dragons, who this weekend host the Vodacom Bulls, DHL Stormers and Emirates Lions.

The Emirates Lions cannot qualify for the play-offs and neither can the Dragons, but the Ospreys and Scarlets are chasing qualification into Europe's knockout competitions through finishing the URC as the leading Welsh team. Both have 44 league points.

It is never easy playing in Wales, both at club and national level, and the South African players, prior to departure for the final round of the competition, all spoke of their respect for the occasion and the strength of the challenge at home.

The Welsh players will be determined to finish on a high and arrive in South Africa in July with the lasting feeling of having downed South African opposition in their final league matches.

It makes the Welsh even more dangerous this weekend.

While all four of the Welsh teams occupy the bottom half of the championship table, and only the Ospreys boast a winning record this season, those selected to tour South Africa will be determined to impress Welsh coach Wayne Pivac.

The timing of Pivac's squad announcement also adds motivation to those Welsh players not selected, which only adds to the difficulty of the matches for the Vodacom Bulls and DHL Stormers, in particular.

The Vodacom Bulls are in sixth place with 53 log points, three in front of Edinburgh and Glasgow Warriors, and three behind the tied trio of Munster, the Cell C Sharks and DHL Stormers, in second, third and fourth places respectively.

Osprey's international veterans Alun Wyn Jones and George North will be at the forefront of the home performance and the entire Osprey's front five will tour South Africa with Wales.

The DHL Stormers have the most realistic shot among the South African teams of hosting a top-eight playoff, but their defence, so impressive this season, will be severely challenged by Scarlets’ seven-man international party chosen to tour in July.

The Scarlets backline is razor-sharp and rated among the URC’s best at cutting the line. Pivac has done a passport check with all of Gareth Davies, Liam Williams, Rhys Patchell, Johnny Williams and Kieran Hardy, a collection of attackers sure to stress-test the Stormers tacklers.

The Lions, despite not being a play-off contender, have individuals knocking on the door of national selection. Primary to these players is the Lions 21 year-old flyhalf Jordan Hendrikse.

South African teams have only won three of 15 matches in Europe this season and the Cell C Sharks, DHL Stormers and Vodacom Bulls must improve that strike-rate against motivated Welsh opposition in Round 18 to bring the playoffs to South Africa.  

It won't be easy, which is a compliment to the strength of the competition that so much will only be decided in the final round of league play.