Heart tests for Boston star Ortiz

The Dominican Republic-born star is vital to Boston's hopes

Red Sox star David Ortiz has checked into hospital for the second time in 10 days to have tests on a heart problem.

Ortiz first complained of an irregular heartbeat after the 13-5 defeat by the New York Yankees on 19 August.

The 30-year-old then suffered a recurrence of the problem before Monday's defeat to the Oakland A's.

"Big Papi" leads the American League with 47 home runs and 121 runs batted in, and is considered the favourite for the AL's Most Valuable Player award.

Red Sox manager Terry Francona said: "We don't feel he's going to keel over. He was tested the other night. A lot of people have these things.

"But he has to know that he is fine. We're not going to jeopardise his health."

To make matters worse for Boston, Ortiz's team-mate Manny Ramirez, who is hitting .326 with 34 homers and 100 RBI, is out until at least Thursday with a sore knee.

And Wily Mo Pena, their other leading offensive player, is currently back in Boston having tests on a left wrist injury.

These problems could not come at a worse time for Boston (71-60), who have lost four straight to fall seven games behind the Yankees in the AL East and six games behind the Chicago White Sox in the wildcard race.

Houston Astros pitcher Roy Oswalt has agreed to a five-year deal worth $73m.

The two-time National League All-Star could have become a free agent after next season, but chose to stay with the team that drafted him in 1996 and for whom he has played his entire career.

Oswalt, who turned 29 on Tuesday, has won 20 games the past two seasons, including last year when the Astros went to their first World Series.

He has compiled a 93-47 record with a career earned run average of 3.09.