WIMBLEDON, England — Wimbledon has always been a haven for fanatical supporters, from the hordes of young women who chased Bjorn Borg around the grounds in the 1970s to the Australians who dress in yellow every year to support their countrymen and women.

Faces will be painted with the Scottish and British flags for Andy Murray over the next two weeks. But fandom can take many forms. Take a look on Twitter during a big Murray match at Wimbledon, and the chances are you will come across the commentary of Irvine Welsh, the Scottish author most famous for writing “Trainspotting,” the anarchic tale of a group of heroin addicts in Edinburgh.

The text of his tweets is often provocative, and the language usually vulgar, but his admiration for the top-ranked Murray comes across loud and clear.

Welsh, who lives in Miami, first tweeted during a Murray match when Murray beat Novak Djokovic in the 2012 United States Open final for his first Grand Slam title.