Wales back-row forward Andy Powell has been ruled out of Saturday's clash against South Africa on Saturday and the two-Test New Zealand tour.
The Cardiff Blues powerhouse had been recalled by Wales head coach Warren Gatland following the infamous golf buggy incident involving Powell during this season's RBS Six Nations Championship.
But he tore a thigh muscle in training with Wales on Tuesday, and his place on the replacements' bench for the Springbok showdown goes to uncapped Scarlets flanker Rob McCusker.
Newport Gwent Dragons flanker Gavin Thomas will take Powell's place on tour, which features games against the All Blacks in Dunedin and Hamilton later this month.
Powell, a British and Irish Lion in South Africa last summer, was axed from the Six Nations squad after he drove a golf buggy while over the limit the morning after Wales' victory against Scotland in February. He was subsequently banned from driving and fined £1,000 by Cardiff magistrates.
But he was set for a chance to redeem himself over the next weeks before injury struck.
Wales physiotherapist Mark Davies said: "Andy has a grade two injury to his left thigh which effectively sidelines him for a minimum of four weeks and leads to his omission from the tour."
Thomas was last capped by Wales on their Australia tour in 2007, and he becomes the second Dragon called up this week after wing Will Harries was summoned to take over from an injured Shane Williams.
Wales assistant coach Robin McBryde added: "Gavin is an experienced player with more than 20 caps who has had some injury problems over the last few years, but he is fighting fit now and has impressed everyone in training.
"It's obviously disappointing to lose someone of Andy Powell's quality, but Gavin now has a chance to make and impact and he, like Rob McCusker, won't be taking that chance lightly.
"Rob has been around the squad for some time, and he was unlucky to miss out on the tour to America and Canada with us last summer after being named in the larger initial squad.
"He is a tough young prospect, and it is only a matter of time before he gets his chance and wins that first cap. If we need him on Saturday he won't let us down."