TOKYO (AP) _ When the Pittsburgh Steelers play the San Diego Chargers tonight, hardly anyone in the crowd at the Tokyo Dome will know that one of the biggest men on the field is half Japanese.

Pittsburgh's left tackle, John Jackson, was born in Okinawa, the son of a U.S. serviceman and his Japanese wife.

Few Japanese would recognize Jackson, a 6-foot-6-inch black man weighing 300 pounds, as one of them. His mother, Mitsue, stands just 4 feet 9 inches tall.

But Jackson, who will start for Pittsburgh when the American Bowl kicks off at 10 p.m. EST, said not even many of his own teammates and coaches know about his Japanese roots.

``That's my personal life and I like to keep it personal,'' Jackson said Friday.

Jackson did say that his mother was born in the Philippines and that her father died there during World War II. Jackson said she taught him some Japanese as he was growing up in Cincinnati.

``I know when somebody's cussing you out,'' he said.

But Jackson has no plans to contact any relatives while in Japan.

``This is business,'' the Pittsburgh Post Gazette quoted him as saying. ``We have a game to play and we're trying to get things done.''

Last year Jackson endured one of the toughest seasons of his nine-year career. He started only nine games in 1995 and missed five because of a knee injury. It was the first extended injury he suffered since he became Pittsburgh's starting left tackle in 1989.

But Jackson returned after surgery to the position he'll play today. Justin Strzelczyk, who filled in for him when he was out, has taken over at right tackle for the departed Leon Searcy.

``We're hoping his knee is stronger,'' offensive line coach Kent Stephenson said. ``It hasn't appeared to bother him much.''

Stephenson believes he has the makings of a good offensive line with Jackson, Strzelczyk, center Dermontti Dawson, right guard Brendan Stai and newcomer Will Wolford at left guard. Wolford is a free agent who spent most of his career at left tackle before moving to guard with the Steelers.

``He is one of our best linemen,'' Jackson said. ``With his experience, he'll help me. He knows what I'm going through. I have to prove some things to myself. I have to get better.''