(UPDATED) SAN FRANCISCO — The marquee matchup of Johan Santana and Randy Johnson highlights the third game of the Mets’ four-game series here against the Giants this afternoon at AT&T Park. Santana could not be any hotter, posting a 0.78 ERA that is the lowest ever by a Mets pitcher after his first seven starts. Unfortunately for the ace lefty, his teammates have scored a total of just 14 runs in those starts — fewest in the majors.

Santana will square off against Johnson, another former lefty Cy Young winner who is obviously in the twilight of his career at age 45 but still capable of a strong outing. Johnson is 6-6 with a 3.79 ERA in 15 career starts against the Mets.

As far as the lineup, Jose Reyes (calf strain) is being held out again. Alex Cora will replace him at shortstop for the third straight game.

Here is the 20-15 Mets’ order for the 4:10 p.m. game:

Luis Castillo 2B

Alex Cora SS

Carlos Beltran CF

Gary Sheffield LF

David Wright 3B

Fernando Tatis 1B

Ramon Castro C

Ryan Church RF

Johan Santana LHP (4-2, 0.78)

Santana’s numbers against the Giants’ hitters

The 18-17 Giants will counter with:

Emmanuel Burriss 2B

Fred Lewis LF

Pablo Sandoval 3B

Bengie Molina C

Randy Winn RF

Juan Uribe SS

Aaron Rowand CF

Travis Ishikawa 1B

Randy Johnson LHP (3-3, 5.89)

Johnson’s numbers against the Mets’ hitters