Davis' home run came in the second inning - a two-run belt that drove in Jones, who had doubled to lead off the inning - tying the game at two and giving Davis a five-homer lead over Miguel Cabrera for the MLB lead.
Jones continued to assault Blue Jay pitching, driving in three runs in the third inning with a three-run shot that put the O's up by a 5-3 score after Edwin Encarnacion had given Toronto a 3-2 lead with a homer of his own in the top of the frame.
Baltimore finished its scoring in the sixth when J.J. Hardy drove in both Jones and Davis with a three-run homer after both base runners had singled to open the inning.
The Orioles kept pace with the Red Sox, who lead the AL East by 4 1/2 over Tampa Bay and have a 5 1/2 game edge on the O's. Toronto fell to 12 1/2 behind with the loss. Game two of the series is slated for 4:05 pm EDT, Saturday in Baltimore
Buster Posey was 2-for-5 to lead the Giants while collecting five RBI to give him 56 on the season.
Posey got things started for San Francisco with a sac fly in the third, tying the contest at 1-1, singled in a pair of runs in the sixth and completed the Giants' output with a two-run double in the seventh inning.
His .320 batting average has Posey tied for fifth in the NL with St. Louis' Matt Carpenter and he is 10th in the league in RBI as the season continues to be one in which pitchers are being belted around in both leagues.
The reigning world champions have fallen on hard times of late, however, dropping 6 1/2 games behind NL West-leading Arizona with a 42-50 mark.
The Padres have fallen to last place in the division, 8 1/2 back, and will host the Giants in the third of the four-game set on Saturday at 7:10 pm PDT.
Today's Trivia: Who was the last player to lead the American League in RBI three straight seasons? (answer tomorrow)
Yesterday's Answer: The only players with 2000 or more RBI are Hank Aaron (2297), Babe Ruth (2220) and Cap Anson (2075).