The Chicago Sky will be without two starters as they head to a place where they rarely win.
Delle Donne scored 13 points in Wednesday's 79-69 loss at Connecticut after missing five games due to Lyme disease. A recurrence of the illness caused her to miss Friday's 73-69 win at New York.
She is out indefinitely, while Vandersloot will be sidelined for 6 to 10 weeks with a sprain in her left knee.
''It's extremely frustrating for (Delle Donne), obviously physically, but it takes a mental toll as well,'' coach Pokey Chatman said. ''She tries to be stoic about everything. But I told her, this thing is real and you are doing the right thing by dealing with it.''
The star forward's absence didn't matter Friday since Epiphanny Prince scored 30 points. Prince matched her season high and is averaging 19.1 points in eight games after missing the first part of the season while taking time to recover from playing in Russia.
''She's a phenomenal player,'' Chatman said. ''She was in rhythm early and has been ever since she rejoined us.''
Prince has never been on a Chicago team that has won in Los Angeles. The Sparks (6-8) are 7-1 at home against the Sky (7-8) and seek a sweep of the season series after a 102-88 victory June 6.
Delle Donne scored 33 points in that contest while Chicago played without Prince and Sylvia Fowles, who are both back now. The Sparks prevailed thanks to a balanced attack with Nneka Ogwumike and former Sky guard Kristi Toliver each scoring 18 points and Candace Parker chipping in with 17.
Parker, the reigning league MVP, is fourth in the league with 19.9 points per game.
Toliver, however, may be the key to the Sparks' championship aspirations. She returned Saturday and made two free throws along with a key 3-pointer in overtime in a 92-89 victory at Tulsa.
The point guard came off the bench to score 12 points after she missed six games while helping Slovakia qualify for the European National Championship. Los Angeles went 2-4 without her.
''That's my job,'' said Toliver, who could start Tuesday. ''That's what I get paid to do. We needed a big basket and that's what I do.''
Parker had an off night with 15 points on 5-of-16 shooting for Los Angeles, which has won consecutive games for the first time. She added a team-high seven assists.
''It's a good win,'' Parker said. ''This is our first back-to-back wins this season. It's obviously great to have Kristi back. She hit some big shots.''
Ogwumike led Los Angeles with 22 points on 10-for-14 shooting
Chicago is 0-4 against Western Conference foes.