Don't be fooled into thinking Carlos Rodriguez is Mr Nice Guy, the guy who merely encourages Li Na with applause and thumbs-ups from the stands.

The soft-spoken Argentine's cheerleading during matches belies a demanding training regime that almost pushed Li to her limits.

"The first time I was training with him, I was so excited. But after three days, I was dying," Li joked of Rodriguez's tough programs after beating Agnieszka Radwanska in the Australian Open quarterfinals on Tuesday.