Lawrence Taylor could begin substance abuse treatment this weekend, but his agent and the team say there is no guarantee the New York Giants' All-Pro linebacker will return to the field when his 30-day suspension ends.

Giants owner Wellington Mara said Tuesday that Taylor would not be allowed to play until doctors running his rehabilitation program are satisfied he has successfully completed it."We owe it to Lawrence Taylor to be as hard on him as we possibly can," Mara said. "That's his only chance to lick this. To be easy on him would be unkind. He has to follow the program 100 percent."

Taylor, a seven-time All-Pro who has been one of football's dominant players this decade, was suspended Monday for 30 days by the NFL for violating the league's substance abuse policy for a second time.

Meanwhile, the New York Daily News, citing unidentified team and league sources, reported today that Taylor failed a drug test following the 1987 season. But the newspaper said Taylor was allowed to take another test, which he passed, a few days later.

Because he passed, the newspaper said, the matter was brushed aside. There was no fine, no rehabilitation and no publicity.

Regardless of what may have happened last season, Taylor may not be given the opportunity to return at the end of his 30-day suspension.

"From what I have read, there is a misconception," Mara said. "This is not a 30-day suspension. This is a 30-day minimum. In order for him to come back, he must follow a rigorous program . . . I think no half treatment is called for."

Taylor has every intention of complying with NFL rehabilitation guidelines and plans to meet with league officials by Friday, said Gary Kovach, Taylor's agent.

"What we are doing is waiting for the NFL to give us our lead and go from there," Kovach said, adding Taylor could begin rehabilitation this weekend.

Kovach said in a telephone interview from his Houston office that league officials would outline the type of rehabilitation program they wanted Taylor to undergo.