Upsets ruled early in the week as the clay season got started with ATP 250 events in Houston and Casablanca. We could see two surprise champions on Sunday with the way things have gone.

Americans Jack Sock, Donald Young and Sam Querrey find form in Houston

Sock won his first two clay matches of the season in Houston, defeating Ivo Karlovic and Benjamin Becker in the first two rounds. Sock now awaits the tough test of Nicolas Almagro in the quarterfinals. Young won on clay for the first time in 12 months as he drubbed Ryan Harrison in the first round and then upset Juan Monaco in three sets to reach the quarterfinals. Monaco has been successful in Houston before and was seeded, so it was an impressive win for Young. He faces a Spaniard, like Sock, in the quarterfinals, as Fernando Verdasco awaits.

Sam Querrey, who has endured a rough season so far, reached his first quarterfinal in 2014 as he scored straight-sets wins against Alex Bogomolov and former Houston champion Lleyton Hewitt. He faces Dustin Brown in a very winnable quarterfinal.

Early-round upset of the week: Dustin Brown d. John Isner 6-4 6-7(7) 7-6(4)

The entertaining, hard-serving Dustin Brown pulled off an upset of Houston top seed and defending champion John Isner in the second round. This was Brown’s first victory over a top-10 player and a victory that knocks Isner out of the top 10 again. Brown held a match point on his serve in the second-set tiebreak, but the American pushed it to three sets. Still, Isner was a miserable 0/9 on break-point chances, and Brown did not miss his second chance to close out the match in the second tiebreak of the evening. The defending champion was extremely disappointed with his performance, while Brown was thrilled to reach the quarterfinals.

Veterans Victor Hanescu, Marcel Granollers, and Benjamin Becker win on clay

These men have not enjoyed strong seasons so far, but they found a bit of luck this week. The 32-year-old Hanescu upset Casablanca top seed Kevin Anderson 6-4 6-4 to reach the quarterfinals. He’ll be an underdog in his next match, but it is his best ATP showing since reaching the semifinals in Stuttgart and Gstaad on clay last summer.

Granollers got a desperately needed win over fellow Spaniard Albert Ramos to reach the quarterfinals in Casablanca as well. He had entered the tournament on a four-match losing streak and has a chance to take the title in a weakened Casablanca field.

Benjamin Becker, another 32-year-old, was ousted by Sock in the second round of Houston. Still, Becker won his first match on clay since 2010 over Ruben Ramirez Hidalgo.  The second round of a 250 event doesn’t seem to be a special accomplishment, but it’s always nice to see players end dry spells, whether large or small.

The Benoit Paire show returns

The entertainingly peculiar Frenchman with the gifted backhand won his first match since the Australian Open against Albert Montanes. Paire dominated this Casablanca encounter but needed three sets to win it.  He failed to serve out the match in the second set, breaking his racquet and calling the trainer in an entertaining moment. Despite those distractions, Paire reached the quarterfinals and has a strong shot at a title this week in Casablanca.

Young-gun qualifiers Filip Peliwo and Roberto Carballés Baena break through in Casablanca

Filip Peliwo, a 20-year-old Canadian, earned his second ATP main-draw win when he upset Italian clay specialist Filippo Volandri after qualifying for the main draw. While Peliwo fell to Federico Delbonis in a spirited three-setter a round later, it was a promising showing for the rising youngster. Look for him to do bigger things in the future.

Meanwhile, 21-year-old Spaniard Roberto Carballés Baena earned his first main-draw win in Casablanca as he upset David Goffin in straight sets after qualifying for the main draw. He then upset fifth seed Joao Sousa in the next round to reach the quarterfinals. Carballés Baena should see his ranking skyrocket from its current position outside the top 250.