Groth won their only previous meeting. That was in April last season on clay. He won in straight sets.
Estrella won the title in Quito on clay last month but that is pretty much his only success in 2016.
Groth has won just 1 match from his last 10. A massive part of his game is his serve and he has lost confidence from the service line.
There is a little value on Estrella. I am sure Groth is working on finding his serve again as his career depends on it. It will click into place sometime soon.
If Groth hasn’t sorted out his serve Estrella takes this.