Since 2006, only five teenagers have managed to reach the men's third round at Wimbledon — and three of them went on to become Grand Slam champions: Novak Djokovic, Andy Murray and Marin Cilic.

So a couple of kids could find themselves in good company if they can add their names to that short list this year.

One, 18-year-old Alexander Zverev of Germany, is in action Wednesday at the All England Club, facing 105th-ranked wild-card entry Denis Kudla of the United States in the second round.

Zverev, who is ranked 74th, won a lengthy opening match Monday, edging Teymuraz Gabashvili 6-3, 1-6, 6-3, 3-6, 9-7.

Of the five teens in this year's draw, only one other remains, 40th-ranked Borna Coric of Croatia, also 18. He won his first-round match Tuesday, and it also ended 9-7 in the fifth set, against Sergiy Stakhovsky. Coric will meet 25th-seeded Andreas Seppi on Thursday with a chance to get to the third round.

Djokovic and Murray both were 19 in 2006 when they reached the fourth round at Wimbledon; Djokovic has since collected eight major titles, and Murray two. Cilic, last year's U.S. Open champion, was 19 when he played in the fourth round in 2008.

The other teens to get at least to the third round since 2006 were Bernard Tomic in 2011, and Nick Kyrgios last year.

Here's what else is happening Wednesday at Wimbledon:

WILLIAMS SISTERS

A day after pulling out of doubles, Serena and Venus Williams are on the schedule in singles. No. 1-seeded Serena takes a 22-match Grand Slam winning streak into her Centre Court match against 93rd-ranked Timea Babos of Hungary, whose career record at majors is 2-11. No. 16 Venus is on Court 2 against 95th-ranked Yulia Putintseva of Kazakhstan.

OLD HAND

At 37, Tommy Haas is the oldest man to win a match at the All England Club since Jimmy Connors was 38 in 1991. After getting past 86th-ranked Dusan Lajovic in four sets in the first round, Haas will have a tougher task in the second round, taking on No. 7 Milos Raonic, who is only 24 and was a semifinalist a year ago. Haas has been ranked as high as No. 2 — way back in 2002 — and participated in four Grand Slam semifinals, including at Wimbledon in 2009. But he's been hampered by injuries, including repeated operations on his right shoulder, most recently in June 2014.

DEFENDING CHAMP

No. 1-seeded Novak Djokovic, the 2011 and 2014 champion, plays 92nd-ranked Jarkko Nieminen on Centre Court. Djokovic has won five of their previous six meetings, including last month at the French Open. He's never lost to a player ranked as low as Nieminen in 228 career Grand Slam matches. Nieminen eliminated 2002 champ Lleyton Hewitt in the first round.

U.S. MEN

Three of the four remaining American men play, including No. 17 John Isner against 148th-ranked wild-card entry Matthew Ebden of Australia, and 52nd-ranked Steve Johnson against No. 11 Grigor Dimitrov of Bulgaria. Dimitrov lost to another young American, Jack Sock, in the first round at Roland Garros.

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