MONTREAL (Ticker) -- The St. Louis Cardinals, who have seen their lead in the National League Central Division dwindle to four games, today addressed one of their biggest weaknesses by acquiring catcher Carlos Hernandez from the San Diego Padres.

St. Louis also acquired minor league infielder-outfielder Nathan Tebbs and sent veteran reliever Heathcliff Slocumb and minor league outfielder Ben Johnson to the Padres. The deal was the Cardinals' third in three days.

Hernandez, 33, should immediately step in as the starter for St. Louis, which has seen projected starter Eli Marrero sidelined by a left thumb injury. Even when healthy, Marrero was hitting just .244 with five homers and 17 RBI in 42 games.

Mike Matheny has filled in for Marrero and is hitting only .237 with four homers and 26 RBI. Matheny suffered a broken rib in a collision at the plate on Friday but played through the pain over the weekend.

Hernandez, who was activated off the disabled list last week, is batting .251 with two homers and 25 RBI in 58 games. He owns a career batting average of .252 with 23 homers and 131 RBI in 10-plus seasons with Los Angeles (1990-96) and San Diego (1997-2000)

On Saturday, the Cardinals acquired righthanded reliever Mike Timlin from Baltimore. Sunday, they picked up Jason Christiansen from Pittsburgh.

"We had three primary concerns to address before the trading deadline," Cardinals manager Walt Jocketty said. "We feel that with today's acquisition of Hernandez, we have accomplished what we set out to do -- improve the bullpen and add a quality catcher."

Tebbs, 27, can play second base, third base or the outfield. He was hitting .256 with two homers and 21 RBI in 133 at-bats for Las Vegas of the Pacific Coast League.

Slocumb, 34, was 2-3 with a 5.44 ERA and one save in 44 games this season. He led all Cardinals relievers with 49 2/3 innings and joins his eighth club in 10 years.

The 19-year-old Johnson was hitting .242 with 13 homers and 46 RBI for Class A Peoria of the Midwest League. Last season he tore up Rookie League pitching, hitting .330 with 10 homers and 51 RBI for Johnson City.

The trade of Hernandez leaves Ben Davis and Wiki Gonzalez as the San Diego catchers.