Detroit ? The Detroit Tigers purchased the contract of infielder Kevin Hooper from Triple-A Toledo before their game against the Los Angeles Angels on Sunday night, adding depth because they don’t know how long Carlos Guillen will be out of the lineup.

Guillen injured his right hamstring after hitting a double in Saturday night’s loss against the Angels.

“I’m never too optimistic about hamstrings,” Tigers manager Jim Leyland said. “That’s why we brought up Hooper.”

To make room for Hooper – a Lawrence High and Wichita State product – on the 40-man roster, Detroit designated infielder Don Kelly for assignment.

Leyland said he had “no idea” when Guillen would be able to play. Second baseman Placido Polanco, out with a left shoulder injury, is expected to be out of the lineup for at least a few more weeks.

Losing both middle infielders hurts Detroit offensively and defensively as it tries to hold onto its lead in the AL Central ahead of the Chicago White Sox and Minnesota Twins.

“We’ll find out how tough we are – how good we are,” Leyland said. “Guys have to step up. There will be no excuses here.

“We have to find ways to win. I won’t put up with any sympathy.”

The Tigers had Ramon Santiago in the lineup at shortstop and Omar Infante at second base in the series finale against the Angels. Neifi Perez, acquired two weeks ago from the Chicago Cubs, and Hooper also are options as middle infielders.

When Guillen and Polanco are healthy, Infante is a seldom-used reserve and Santiago is usually in the minors. The Tigers traded for Perez two weeks ago, shortly after Polanco was hurt making a tumbling catch at Boston.

Guillen is hitting .310 this season with 17 homers and 73 RBIs. Polanco is hitting .294 with 17 doubles and 44 RBIs.

Hooper hit .276 in 121 games in Toledo with a homer, 29 RBIs and 24 stolen bases. He made his major-league debut on July 9, 2005, and had a single in five at-bats over six games.

He was used as a pinch runner Sunday night and did not record an official at-bat in the Tigers’ 2-1 loss to the Angels.