Mmoh, Rubin, Tiafoe, McDonald Reach Stockton Challenger Semifinals; Semifinals Set at Women's ITA Riviera All American Championships, Top Seeds Advance at Men's All American

The quarterfinals at the $100,000 ATP Challenger in Stockton, California could hardly have gone better for the young Americans, with four of them, all aged 21 and under, advancing to Saturday's semifinals.

Frances Tiafoe, the only one of the four seeded at No. 3, defeated No. 6 seed Alessandra Giannessi of Italy 7-6(5), 6-3 and will play McDonald, who came back for a 3-6, 7-6(1), 6-4 win over No. 5 seed Denis Kudla. The 21-year-old McDonald, who reached the semifinals last week at the $100,000 by beating Tiafoe,  received a special exemption into this week's tournament and has now earned another for next week's $100,000 event in Fairfield, California.  Regardless of who wins Saturday's semifinal, both McDonald and Tiafoe will reach career highs in their ATP rankings.

The other all-American semifinal will feature 20-year-old Noah Rubin against 18-year-old Michael Mmoh.  After five straight-sets losses to Canadian Frank Dancevic in the past two years, Rubin finally got a win today, taking their quarterfinal 4-6, 6-2, 6-3.  Mmoh avenged his loss to Darian King of Barbados in last week's Tiburon final, adding credence to the theory that Mmoh, a qualifier, was just out of gas in his eighth match of the tournament in that final.  Mmoh defeated King 6-4, 6-4, facing only one break point, which he lost, in the match.

Although the professional head-to-head shows nothing for Rubin and Mmoh, they played two years ago in the semifinals at Kalamazoo, with Rubin winning a tense 7-6(1), 2-6, 7-5 encounter and going on to claim the title, as Mmoh did this year(with much less drama).

Live streaming with commentary by the excellent Mike Cation is available for both matches here.

At the $25,000 USTA Women's Pro Circuit event in Redding, California, Danielle Collins' run came to and end.  Collins, who won last week's tournament in Stillwater, Oklahoma, fell to top seed Sachia Vickery 6-4, 6-4 in today's quarterfinals.  Wild card Julia Elbaba, like Collins, a recent Virginia graduate, lost to No. 2 seed Francoise Abanda of Canada 4-6, 6-2, 6-4. Bernarda Pera won her match over German Lauren Schaeder 7-6(6), 6-0 and will play Abanda next.  Vickery gets qualifier Katie Boulter of Great Britain in the semifinals.

At the Saint Francis Health System ITA Men's All-American Championships in Tulsa, the top six seeds have advanced to Saturday's singles round of 16, with only two seeds losing in second round action today.

Qualifier Christian Seraphim of Wake Forest defeated 9-16 seed William Bushamuka of Kentucky 6-4, 6-4 and Alfredo Perez of Florida beat No. 7 seed Arthur Rinderknech of Texas A&M 6-4, 3-6, 6-4.  Seraphim gives the Demon Deacons three players in the round of 16, the most for any school, joining teammates Petros Chrysochos, the No. 6 seed, and No. 5 seed Skander Mansouri.

Top seed Mikael Torpegaard of Ohio State advanced with a 6-2, 6-2 win over Aron Hiltzik of Illinois, but it was definitely more difficult for No. 2 seed and defending champion Thai Kwiatkowski of Virginia, who prevailed over UCLA's Martin Redlicki 3-6, 7-6(3), 7-5.

The remarkable run of Texas freshman Christian Sigsgaard continued, with the 19-year-old from Denmark winning his ninth match in the past seven days.  Sigsgaard defeated Herkko Pollanen of Ohio State 2-6, 6-3, 6-3 to join fellow Texas freshman, qualifier Yuya Ito, in the third round.

At the Riviera/ITA Women's All-American Championships, two round of singles were played today, with top seed Hayley Carter of North Carolina and No. 3 seed Francesca Di Lorenzo of Ohio State winning both their matches to advance to a semifinal meeting Saturday.  Carter defeated Erin Routliffe of Alabama and Viktoriya Lushkova of Oklahoma State, setting a new school record for most singles wins, while Di Lorenzo got by Lily Miyazaki of Oklahoma and No. 6 seed Belinda Woolcock of Florida.  Di Lorenzo trailed Woolcock 5-0 in the first set before roaring back for a 7-5, 6-2 victory.

In the bottom half of the draw, pre-qualifier Ena Shibahara of UCLA got off to an even worse start than Di Lorenzo, losing the first set of her quarterfinal match with Florida's Kourtney Keegan 6-0, but she then claimed ten games in a row before earning a 0-6, 6-0, 6-2 victory, her ninth in seven days.  After seven consecutive straight-sets victories, the freshman needed three sets in her first match of the day too, beating Vladica Babic of Oklahoma State 2-6, 6-3, 6-2.

However inhumane it may seem, Shibahara's run is not unusual. In 2012 Virginia freshman Julia Elbaba came through pre-qualifying to make the final, and the following year, North Carolina freshman Jamie Loeb came through pre-qualifying to win the title.

Shibahara will play Vanderbilt's Astra Sharma in the semifinals, with Sharma taking out North Carolina freshman Sara Daavettila and Pepperdine's Mayar Sherif Ahmed.

The doubles semifinals are set for Saturday, with the unseeded team of Carter and Jessie Aney facing Northwestern's Alex Chatt and Maddie Lipp, the No. 7 seeds, in the top half. In the bottom half, No. 2 seeds and NCAA champion Keegan and Brooke Austin of Florida will play Pepperdine's No. 5 seeds Luisa Stefani and Apichaya Runglerdkriangkra.

Matches will be streamed for both All-American Championships at FloTennis.com, with a subscription payment required for viewing.