Serena Williams was stunned to win the 'Serena Slam' for the second time.

After 12 years, the world number one American tennis player has once again become the reigning champion of all four Grand Slam tournaments, despite being almost 34 years old. She also has the opportunity to win all four major titles in the same year for the first time.

“I can’t believe I’m still here, participating in this tournament and completing another Serena Slam. It’s amazing. I’m so happy and honored to have had so many years of success at Wimbledon. The fans have helped me overcome so many challenges. I was playing on the court but I could clearly hear everyone shouting ‘I love you.’ And I love you all too. It’s an honor to have this support,” Serena said after her Wimbledon final victory over 21-year-old Spaniard Garbine Muguruza.

Serena is thrilled with her grass court Grand Slam title. Photo: Reuters.

This is the second time in her career that the younger Williams sister has achieved a "Serena Slam," meaning she holds all four Grand Slam titles simultaneously. Following her US Open title at the end of 2014, Serena has consecutively won the Australian Open, the French Open, and now Wimbledon. A similar feat occurred 12 years ago, when she won the French Open, Wimbledon, and the US Open in 2002, and added the Australian Open in early 2003.

Regarding the 2015 Wimbledon final, Serena commented: “The match was exciting and I felt very good about it. Garbine played very well. She started brilliantly and fought hard at the end, making it take me a moment to realize the match was over. She will win the title soon, if she can continue what she showed at Wimbledon this year. I am happy that it was a great final.”

Immediately afterwards, Serena turned to Muguruza while they were both being interviewed and said, "Congratulations. Don't be sad about this match. You will win this championship in the near future, very soon. Trust me."

Muguruza showed great potential by reaching the final of this year's tournament. Photo: Reuters.

Serena's first Wimbledon title since 2012 is not simply her 21st Grand Slam singles title in her illustrious career. It also brings her closer to achieving an unprecedented feat. If she defends her US Open title later this year, Serena will become the first female player since Steffi Graf in 1998 to win all four Grand Slams in a single season. She also needs just one more Grand Slam to equal Steffi Graf's record of 22 Grand Slams (the Open Era record).

At the age of 33 years and 289 days when she played in the final, Serena became the oldest female tennis player to win a Grand Slam title in the Open Era, surpassing the previous record held by legend Martina Navratilova (who won Wimbledon in 1990 at the age of 33 years and 263 days).

Meanwhile, Muguruza stated: "I am very happy and proud to be playing in front of such a wonderful crowd. I love playing on big courts, and a Grand Slam final is like a dream come true for me. I also want to congratulate Serena. She has shown us all that she is still the world number one."

According to VNE