Old-spec engines will be mandatory for this year's running of Formula 3's most-important race, the Macau Grand Prix.
The FIA World Motor Sport Council confirmed today that only engines running to 2012 specification - as used in this year's F3 European Championship - will be allowed, and that the new-spec engines used in the Japanese championship will not be permitted.
AUTOSPORT first hinted on April 30 that the FIA looked increasingly likely to implement such a rule.
The decision makes it very difficult for Japanese teams - who would have to revert their cars to pre-2013 specification - to compete.
But it will also make it significantly easier for European teams, who would otherwise have faced an almost impossible task in converting their cars between the end of their championship season in late October and transportation to Macau in early November.
For the full FIA World Motor Sport Council decision, click here