Crossword puzzle clue "it's open to attack"

"Attack!", to an attack dog

It's open to attack

Rare occurrence at the U.S. Open on Father's Day that's a common occurrence at the U.S. Open on Labor Day

US Open and French Open feats

2004 French Open and U.S. Open runner-up Dementieva

Woman who won the Australian Open and US Open in 1997 without losing a set: 2 wds.

Tennis player who has won an Open Era record six women's singles titles at the Australian Open: 2 wds.

Australian Open and French Open, familiarly