All the matchups between these right-handers came over the previous two years. Cain (7-7, 4.47 ERA) went 1-0 with a 2.07 ERA, 17 strikeouts and five walks in those games and Norris (8-9, 3.78) was 0-1 with a 2.75 ERA, 22 strikeouts and nine walks.
They each lasted at least six innings every time and only once did either allow more than two runs, with Norris yielding three last July 12 in a 3-2 defeat with Houston. That was the only meeting in which they received decisions with Norris' Astros winning 4-3 on Aug. 28, 2011, and the Giants posting a 3-2 victory exactly one year later the last time they met.
Both starters may have to be stingy based on run-support averages of 3.65 for Norris and 3.76 for Cain.
"We're not worried about the offensive guys, they're going to do their thing," said Cain after he gave up two runs over six innings in Tuesday's 3-1 loss to Milwaukee. "We've just got to keep going out there and throwing the ball well."
Of course, Norris has a better offense backing him since being acquired by the Orioles on July 31. He has yielded three runs over 12 innings in winning his first two outings with Baltimore.
"He's fitting right into the mold of the team," center fielder Adam Jones said. "It's no-nonsense, get the job done and no excuses. He's given us a big lift."
Cain is 2-1 with a 2.00 ERA over four starts since the All-Star break as he finally faces Baltimore (64-52), which will leave Tampa Bay and Minnesota as the only clubs he has never started against. He last faced major league home run leader Chris Davis in 2009, with Davis going 0 for 3 with two strikeouts with Texas.
Davis is clearly a different player now, homering twice and driving in seven runs halfway through this eight-game trip. He hit his major league-leading 42nd homer in Saturday's 3-2 loss but also grounded out against closer Sergio Romo to end the game.
San Francisco (52-64) improved to 4-9 in interleague play as Hunter Pence hit a go-ahead, two-run double in the sixth inning.
"We got the hit we've been looking for," manager Bruce Bochy said. "It's the type of hit that wins ballgames for you and has been missing. It's good to get those timely hits. You hope guys relax a little bit and start having more fun."
Jones has never faced Cain but is 15 for 31 during an eight-game hitting streak.
Brandon Belt is 10 for 21 with seven runs scored in his last six games, but is 1 for 8 against Norris.
Pablo Sandoval, meanwhile, is hitless in his last 17 at-bats as part of a 2-for-32 slide. He's 2 for 9 versus Norris.