Four years after being on top of the women's tennis world, Serbians Ana Ivanovic and Jelena Jankovic are struggling with their confidence and mental toughness in trying to find a way back to the top.
"Well, the bottom line is this is a mental game in the end," said reigning US Open men's champion Novak Djokovic. "Everybody is practicing really hard. There's a lot of competition out there.
"Mentally they need to overcome the pressure, the issues, and start believing on the court that they can actually do it."
Ivanovic, the 12th seed, defeated Ukraine's Elina Svitolina 6-3, 6-2 on Tuesday to reach the second round of the US Open while Jankovic, seeded 30th, was to face another Ukrainian, Kateryna Bondarenko, in a later opening match.
Ivanovic won the 2008 French Open and spent 12 weeks as World No. 1 but has not reached a Grand Slam quarter-final since then. Her only titles since then have been two each at Linz and Bali, both on indoor hardcourts.
Jankovic lost to Serena Williams in the 2008 US Open final in her only Grand Slam title match.
She has reached five other Grand Slam semi-finals, most recently at the 2010 French Open, but otherwise has not gone deeper than the fourth round since her finals loss at Arthur Ashe Stadium.
Jankovic, 27, spent 18 weeks atop the rankings in 2008 but has not won a title since 2010 at Indian Wells, although she reached the final last week at Dallas and in June at Birmingham.
Asked how his compatriots could return to glory days, Djokovic said they must improve their mental game.
"Because Jankovic was No. 1 in the world, Ivanovic too -- she won a Grand Slam, that means they have the quality and ability to do so," he said. "I sincerely hope they will again."
Ivanovic, 24, agreed that years of being unable to follow up on her one-time Grand Slam success have taken a toll.
"Yeah, it is a lot to do with confidence," Ivanovic said. "Also since the time I entered, the game has evolved and there are lot more girls that strike and they have nothing to lose.
"They play really well and they are very dangerous. But definitely it's just not the belief of beating those top players at the moment."
"I evolved as a player. I added a little bit more to my game. It's just a matter of putting it together in the big matches and believing in it."
It did not help that she lost 6-0, 6-0 to Italy's Roberta Vinci in her only US Open tuneup match.
"It's tough. It wasn't easy," she said. "Sometimes when you get overexcited it doesn't really work."
Ivanovic has never been past the round of 16 at Flushing Meadows, reaching the fourth round the past two years to match her best US Open result.
"My big goal is to break the fourth round and get into quarter-finals," she said. "It's not easy. There are so many dangerous opponents out there."