Aches and pains from a heavy weekend workload have knocked both Simona Halep and Garbine Muguruza out of Stuttgart.
Reigning Roland Garros champion Halep withdrew with a left hip injury.
More: Garcia, Mladenovic Lift France To Fed Cup Final
Halep won two singles matches and partnered Monica Niculescu in doubles as Romania fell to host France, 3-2, in the Fed Cup semifinals in Rouen on Sunday.
"If I'm not 100 percent, I don't want to step on the court," Halep told the media in Stuttgart. "I'm also exhausted mentally because I gave my everything in that tie but unfortunately we couldn't win."
The world No. 2 aims to return for Madrid and Rome ahead of her Roland Garros title defense.
"That's why I decided to pull out, because I have to think about my health first. "I've been very sad the last two days. I've been through these moments many times, so I know how to handle it. I just need to recover mentally and physically and then just start again."
Two-time Grand Slam champion Muguruza, who also played three matches in Spain's Fed Cup World Group Playoff triumph over Belgium, is out with illness.
Vera Zvonareva has replaced Halep in the draw.
Photo credit: Lindsey Godwin/Miami Open