The former world No. 5 is into the Bogota quarterfinals with underarm serving. (AP)

Nick Kyrgios must be reeling right now. Sara Errani is in Bogota this week hitting mostly underarm serves. The world No. 243—on the comeback trail from a doping suspension—made the quarterfinals of the WTA International as a lucky loser.

The only issue is that the nine-time WTA champion seems to have forgotten how to serve. 

The former world No. 5 been struggling heavily with her ball toss, needing three or four attempts before serving.

She hit 18 double faults in each of her first three matches in Bogota, including her her first-round qualifying win over Danielle Lao, her qualifying loss to Jasmine Paolini and her first-round win over Irina Bara. 

Against qualifier Bibiane Schoofs on Thursday, the 31-year-old made a change, and started serving underhand a lot more times than what she tried against Bara. 

Most interestingly, the 2012 French Open finalist reverted to the underhand strategy largely on her second serves. She hit just four double faults in her 6-2, 6-1 win over Schoofs, marking her first straight-set match in Bogota. 

Her serving woes didn't just start in Bogota. Errani has been double faulting all season, with 22 struck in win over Irina-Camelia Begu in Guadalajara and 18 in a win over Heather Watson in Indian Wells.  

The Italian served a 10-month suspension in two parts after testing positive for the banned drug letrozole, a substance her mother used for breast cancer treatment. She made her return in February this year, and ultimately lost to Astra Sharma in the quarterfinals on Friday, 6-1, 7-5.