Richards faces the Arizona Diamondbacks for the first time Sunday when the Angels try to win their sixth consecutive interleague home series and move a season-high five games above .500.
Out since May 29 with a lower back strain, Weaver appears to be recovering nicely after throwing a pain-free 60-pitch simulated game Friday.
The right-hander is scheduled to have a bullpen session Sunday when Scioscia said the team will "make a determination of exactly where he is."
For now, Richards (1-0, 1.38 ERA) is in the rotation as he gets set to make his third straight start in place of Weaver.
But after Santana's one-hitter in Saturday's 2-0 victory, it's uncertain how long the rookie right-hander will keep taking the ball.
Possibly pitching for his spot in the rotation after going 1-1 with a 10.18 ERA in his previous four outings, Santana retired the first 20 batters he faced - Justin Upton broke up the perfect game with a single - as the Angels rebounded from Friday's 5-0 series-opening defeat.
"If (Santana) commits, that's what he can do," Scioscia said.
The Angels (35-31), winners of 27 of 39 against NL teams, have not lost a series at home during interleague play since June 14-16, 2009, against Milwaukee.
Richards will try to keep it that way. In his last outing, he did not earn a decision after walking a career-high five in five innings of Monday's 3-2 road win over the Los Angeles Dodgers.
The Diamondbacks (32-33), losers of six of eight to the Angels, close out their six-game trip with Ian Kennedy (5-6, 4.32) on the hill.
The right-hander needs to improve after surrendering a season-high 10 hits and six runs in Tuesday's 9-1 loss at Texas. He had an 0.66 ERA while winning each of his previous two outings.
Kennedy, who is 0-3 with a 10.91 ERA in his last three interleague starts, will face the Angels for the third time, and first in a Diamondbacks uniform.
In his only start against the Angels, the right-hander was tagged for five runs in two innings of a 10-5 New York Yankees road loss Aug. 8, 2008.
It is the shortest of Kennedy's 90 career starts.
Albert Pujols, 1 for 3 with a double off Kennedy, could return to first base Sunday. He went 0 for 4 as the DH on Saturday after fouling a ball off his shin in the series opener.
Center fielder Peter Bourjos is expected to make his first start for the Angels since June 6 on Sunday.
Angels right fielder Mark Trumbo is batting .386 with seven homers and 20 RBIs in Anaheim after hitting a two-run shot Saturday - his team-leading 15th homer.
Upton is hitting a team-best .366 as the Diamondbacks have a 7-4 record against the AL in 2012.
The Angels have won 11 of their last 12 interleague series.
- Jered Weaver
- Ervin Santana
- Mike Scioscia
- Arizona Diamondbacks
- Los Angeles Angels