Stop four of seven on the Arena Pro Swim Series is this weekend in Mesa, Arizona. Things start on Thursday with the men’s and women’s events in the 200m freestyle, the 100m breaststroke, the 100m butterfly, and the 400m medley.

Headlining the women’s 200m freestyle is Katie Ledecky, who has the won the first three races of the series, Missy Franklin, who has two seconds and a third, and Allison Schmitt who finished third in both of the races she took part in.

In the men’s 200m freestyle Connor Dwyer has won both of the races he entered so far this season while Ryan Lochte and Townley Haas came in second in their only races. Michael Phelps has a tenth and fourth place finish to show after his first two races of the year.

Over in the women’s 100m breaststroke the top American contenders include Katie Meili, who won the event in Austin, Micah Lawrence, who came in second in Minneapolis, Andee Cottrell, who was third in Minneapolis, and Molly Hannis, who has a second and third in her two races this year.

The men’s 100m breaststroke doesn’t feature many of the top finishers so far this season but one of the top contenders will be Andrew Wilson who won this event in Austin.

Both Kelsi Worrell, first in Minneapolis, and Dana Vollmer, second in Minneapolis and Austin, are strong contenders in the women’s 100m butterfly while in the mens 100m butterfly Giles Smith has three top five finishes including a win in Minneapolis.

Finally in the women’s 400m medely Becca Mann has notched two runner-ups and a third place finish to start the year while Tyler Clary has a fourth and a second in his two events so far this year.

The preliminaries are in the morning with the final in the evening and then we’ll know the eight event winners from the first day of the Mesa stop of the Arena Pro Swim Series.