Serena Williams grabbed yet another major title on July 11 to complete a second Serena Slam and bring her major total to 21 -- one less than the record held by Steffi Graf. Williams, the number one ranked player, faced quite a few obstacles on her path to the 2015 Wimbledon championship. However, none of those bumps in the road were enough to stop Williams from balancing the heavy Wimbledon plate on her head in celebration.

At many points, Williams found herself in trouble. In the third round of Wimbledon, Williams lost the second set against British player, Heather Watson, only to come back and finish the match 7-5 in the third set. Although Williams’ next match wasn’t as physically challenging, she remained in constant emotional turmoil as she faced her sister Venus Williams in the fourth round. But Serena’s admiration and love for sister did not slow her down. She stormed through the match in two straight sets, beating her sister 6-4, 6-3.

With hardly any time to regroup, Williams headed into the quarterfinals to face the number 23 rank, Victoria Azarenka. Having played Azarenka multiple times before, and even struggling against her in the 2012 Madrid Open, Williams knew this would be no easy win. She came into the game, seemingly, shaken by Azarenka’s persistence and fierce energy. She lost the first set 3-6, after which Azarenka celebrated. Williams could be seen giving Azarenka and the cameras a look of frustration and, what we discovered to be, determination. Williams’ mental toughness allowed her to return to the court refocused, instead of distracted and tense. She answered Azarenka’s cheer with a higher level of play and a confidence characteristic of Williams later in her matches. She stole the second and third sets from Azarenka (6-2,6-3) and continued her quest for the championship.

Williams’ semifinal match was one of great anticipation, as she faced what the media called her "longtime rival,” Maria Sharapova. Although Williams had won 16 of their 18 head-to-head matches, Sharapova fought her way to the semifinals unscathed and made her presence known. Many wondered if Sharapova would reclaim her dominance over Williams. But Sharapova’s efforts were no match for Serena’s powerful serve and her speed on the grass courts. Williams defeated Sharapova in two straight sets: 6-2, 6-4.

Williams was one match away from her 21st title, her second Serena Slam, and a chance to complete a calendar Grand Slam this year. Set to face Garbine Muguruza in the Finals, Serena was on high alert. Muguruza, ranked No. 20 and equipped with enough power to throw Williams off track, would be a challenging opponent. Muguruza lost control of her nerves midway through the match and gave Williams a dangerous advantage. Williams took full control and came out victorious, dropping Muguruza in two straight sets.

Not only is Serena Williams physically dominant, her mental toughness is unprecedented. Able to come back from large deficits and to maintain focus when frustrated or emotionally affected, Williams proves that it is her mental toughness that sets her apart. Many opponents had the speed and the strength to end her Wimbledon run. Recently in her last major, Williams played with the flu during the French Open and still managed to fight her way to another title. Williams has trained herself to stay focused on one task, and one task only: to be the best. Her mental strength makes her almost impossible to defeat.