Anthony Joshua will make the third defense of his IBF heavyweight title and looks to win the vacant WBA heavyweight title Saturday against former two-time heavyweight champion Wladimir Klitschko.

Joshua has knocked out all 18 of his opponents and has both the longest active knockout streak and highest knockout rate among current titlists.

Joshua off to fast start

Joshua has become the face of the United Kingdom boxing resurgence. The U.K. has tied Mexico for the second-most titleholders in the world: 11 belts in 10 weight classes. Joshua began his career on a tear and won the IBF heavyweight title in his 16th professional fight, which ranks as the fifth-fastest heavyweight title win all time.

Klitschko is best-known for using his jab to keep opponents at a distance. He ranks third among all CompuBox-tracked fighters in jabs landed per round (8.7) and jab connect percentage (30.1 percent).

The jab also works to his advantage defensively. His opponents land 5.4 total punches per round against him, which ranks second among active CompuBox-tracked fighters, and land 22.3 percent of their total punches, which ranks 10th.

History on the line for Klitschko

Joshua is 27 years old, and Klitschko is 41. This is the ninth-widest age gap between heavyweights in a title fight. The last time there was an age gap larger than this fight, Klitschko (26) was the younger fighter, taking out former titlist Ray Mercer (41).

Klitschko could add another accolade to an already historic career. He can become the second man to win a heavyweight title belt past the age of 40, joining George Foreman, who knocked out Michael Moorer at age 46 to win two belts in 1994.

A win would also place Klitschko on a list of three-time heavyweight title winners that includes his brother Vitali, Muhammad Ali, Lennox Lewis and Evander Holyfield, who won it four times.

Klitschko could tie Joe Louis and Floyd Mayweather Jr. with 26 title-fight wins for the third-most in history.

This fight aside, Klitschko’s career has already been an all-time great one by the numbers. His 18 consecutive heavyweight title defenses (from 2006 to 2015) rank third all-time among heavyweights behind Larry Holmes (20) and Joe Louis (25). The nine-year, 222-day span as champion was the second-longest reign for a heavyweight behind Louis, who was champion for more than 11 years.