It was the best of days for Donald Young at the U.S. Open Monday and the worst of draws for Scoville Jenkins, two low-ranked young pros from Atlanta, struggling to join fellow African American No. 6 James Blake in the top 100 of the ATP Men’s tour.

In a battle of lefties, Young, No. 223 in the world, finally finished a Grand Slam first round with a smile, rallying to beat No. 93 Chris Guccione 6-7 (2-7), 6-3, 6-2, 6-3 in two hours, 30 minutes. “It’s awesome,’’ said Young, 18. “The first five-set match I’ve won. First one at the U.S. Open after three tries. It’s great.”

A few hours later, No. 319 Jenkins, a qualifier, made another quick exit. Three years ago, Jenkins, 21, was trounced by Andy Roddick in the first round. In 2005, he lost to Rafael Nadal in the second round and last year, he was thumped by Jonas Bjorkman in the first round.

Today, top-ranked and three-time champion Roger Federer sent Jenkins packing, 6-3, 6-2, 6-4 in hour, 32 minutes. Slowed with a wrist injury, remains confident that his ranking will continue to rise.

“This is just another step for me to get to the next step,” Jenkins said. “You always want to play on a big stadium against No. 1 in the world. You really can’t ask for more than that.”

Though he didn’t beat a top seed, Young gained more confidence just by reaching the second round at a Grand Slam event for the first time. Young, who turned pro three years ago, won his first tour level match last week in New Haven, after losing in the first round 11 consecutive times. Did he wonder if he he’d ever break the losing streak?

“Obviously, that goes through your mind when you lose 11 in a row,’’ Young said. “But I felt I would win at least one. I knew I would get one.”

Young, not quite a six-footer with a slender build, turned pro in 2005, after finishing the year as the No. 1 junior in the world. Former pro John McEnroe was his primary supporter.

“I had the strokes, I had the game, I thought I could play with them but physically, I couldn’t last,” Young said. I was 15 they were like 20, grown men. It’s different.”

Jenkins, slightly taller at 6-2 and a solid 170 pounds, has the size, but playing Federer, he says, helped him realized that he has more work to do before he’ll have the mental toughness and experience to challenge the top-ranked pros.

“Mentally, you know that he’s going to be sharper,” Jenkins said. “He just plays you, trying to make you play your worst (while) he plays his best. He matches up his strength to your weaknesses unbelievably. It’s very mentally frustrating.”

Both players said they were proud to be competing on the same day that the late Althea Gibson, the first African American to compete at the U.S. Open (known as U.S. Nationals before 1968), would be honored. “(She) probably changed the sport for African Americans,” Jenkins said. “I’m very lucky to be playing today.”