Roger Federer on Monday joined in the call first made by Andy Murray for more blood doping tests in tennis to make sure that the sport remains as clean as he believes it already is.
The Swiss world No.2 said at the Rotterdam World Tennis that the object should be to make sure that players were dissuaded from the temptation to cheat by the certainly that they would be caught.
"We should do more in terms of blood testing," said the 31-year-old. "I also support the biological blood passport, with information stored away. It's important to make sure that tennis is credible and clean to a maximum.
"We don't want players even getting the idea to cheat. Of course we need more funding. Maybe the Grand Slams should put in more since they have the most to lose if one of their players is not clean.
"I feel tennis is very clean, there's maybe one case a year and they are not all done on purpose. Some are just mistakes, but stupidity can get you into trouble also."
Federer is top seed at the indoor event which he won in 2005 and last season.