AceShowbiz -

Gwen Stefani took his youngest son Apollo to the 2014 U.S. Open at USTA Billie Jean King National Tennis Center on Thursday, September 4. The No Doubt member, who sported a black leather jacket and full makeup, held her adorable 6-month-old son who wore a colorful jacket, black pants and socks.

During the game between Switzerland's Roger Federer and Gael Monfils of France, the coach on "The Voice" was seen having FaceTime session with her other sons who were at home. The singer later also had a chance to take a selfie together with Federer. "Omg!! #goroger #usopen2014 #urmagic gx," she captioned the snap.

The day before, Stefani made an appearance on "Late Night With Seth Meyers" where she commented that Apollo is "miracle" baby. She said that baby Apollo was conceived following weeks of prayers from her son Kingston. "He has a direct link to God, basically," she joked. "He asked me, 'Mom, are you gonna have a baby? I want you to have a baby.' "

Stefani did not plan to have another child, but she eventually got pregnant. "I swear to you, he prayed every single night. And four weeks later, I was pregnant!" she said.

The mother of three was most recently seen at the presentation of her L.A.M.B. collection at New York Fashion Week on Friday. On the second day of the fashion event, Stefani presented the new collection of clothes and debuted new shoes and bags while wearing a pink-and-black patterned jumpsuit.