Police are investigating after the four-time world bowls champion had three of his four specially created Glasgow 2014 competition woods taken in a break-in of the men's locker room at the Troon Portland Club.
Bizarrely, the remaining one was removed from his trolley bag and left behind in the club locker room - which Foster believes was a calculated act.
"There is a lot of jealousy involved [in bowling circles]," said the Troon-based bowler, who is ranked number one in the world.
"I mind my own business and get on with things. There are people who don't like you, you just have to accept that."
"My impression is that someone's tried to sabotage, to get into my head, for the Commonwealth Games. They don't want me to do well. To take three bowls is no use to anyone. It's obviously a prank towards me. It's as if to say, 'stuff you, we've left you one bowl and that's no use to you'. "
Foster, who is known by the nickname Fossie, is now scrambling to find replacement bowls and begin intensive practice to get used to them, with the Glasgow Games just a fortnight away.
It is believed the bowls were taken between 4pm and 5.45pm as Foster was heading to the clubhouse. The 41-year-old taxi firm proprietor, who became four-time winner of the men's singles in the World Indoor Bowls Championship, has been playing and practising with the bowls intensively since the Spring, in readiness for his part in the Team Scotland pairs and fours events at the Games.
The missing bowls are Henselite-manufactured Tiger Bowls Size 4, a royal blue wood with white speckles and featuring an engraving - in white paint - of Kelvingrove Museum and Art Gallery which provides the backdrop for the bowls tournament.
The Commonwealth bowls competition will be played on the lawns beside Kelvingrove in Glasgow's west end.