"The important thing for Shane is that when he gets a chance in the first few games he gets the form back that he had last season," said Gatland, who led Wales to Grand Slam glory last year with Williams playing a key role in that success.
"He has not been quite playing as well as he did last season, but when he is on form we know what he can do.
"Shane is an incredible talent and a match winner."
Having achieved so much in 2008, Williams' performances have closely scrutinised this season, especially as both his club side the Ospreys and Wales ended the season without any silverware.
Gatland, however, has told his star man that the current Lions tour is the perfect place to get back to his best and the Kiwi fully expects Williams to start that process during Saturday's opening tour match at the Royal Bafokeng Sports Palace.
"Sometimes this season, with the pressure he is under, there has been a tendency when things have not quite been going right for Shane to try too hard. When that happens, mistakes can follow.
"We saw it with Bryan Habana the year after he was world player of the year and he did not play so well.
"But Shane is coming back to his best form, so he can just relax and enjoy his rugby out here."