The Seattle Mariners knew Carlos Guillen, Alex Rodriguez's able replacement as their starting shortstop, was sick. They just didn't know how sick.

"It is as big a shock to me as it is to you," Dr. Mitch Storey said after the team's medical staff diagnosed Guillen with pulmonary tuberculosis. "We are trying to figure out just exactly what this is going to mean for Carlos."

The Mariners (110-44) beat the Oakland Athletics 5-3 Friday night with a lineup that had rookie Ramon Vazquez starting in Guillen's place at shortstop. Vazquez also was expected to be in the Seattle lineup Saturday night against the A's, too.

Mark McLemore, Seattle's super utility player, who has spelled Guillen at shortstop this season, is sidelined with a sore knee that is expected to keep him out until Tuesday.

Manager Lou Piniella hopes to have Guillen ready for his AL West champions' first playoff game Oct. 9, but he stressed the main concern was Guillen's health.

"He hasn't been feeling good for a while," Piniella said.

Because tuberculosis is a contagious disease that spreads through the air like the common cold, the Mariners players were concerned about their own health and the health of their children as well as the health of Guillen.

"Most of the guys are concerned about their kids," centre-fielder Mike Cameron said. "I don't want to tell my wife about it because she'll go ballistic. We all fly together, and Carlos has been sick for a while."

Guillen, a 25-year-old Venezuelan, was immediately put in quarantine, meaning he won't be able to go near his teammates for at least a week.

"But if everything goes well, we hope Carlos will be playing in one week and we anticipate him to be available for the playoffs," Storey said.

Seattle's Ichiro Suzuki, who tied Shoeless Joe Jackson's major league rookie record of 233 hits with a pair of infield singles Friday night, said the quiet-spoken Guillen is one of his favourite teammates.

"He's been very kind and very friendly to me," Suzuki said. "I hope he's going to be available for us for the playoffs. For his sake and ours."

Right-hander Paul Abbott said he was "shocked" when he found heard about Guillen on Friday night because he had assumed that tuberculosis was a disease that had been wiped out in the United States a long time ago.

"I've never heard of anyone else having it," Abbott said.

But Jason Isringhausen, the A's closer, was diagnosed with tuberculosis in May 1997 when he was with the New York Mets. He didn't miss any playing time because he had a broken wrist at the time, but spent two weeks isolated in a hotel in New York. He had to take antibiotics for 9 1/2 months.

It wasn't a lot of fun, he recalled.

"I woke up one morning, and I couldn't breath," Isringhausen said. "I had a growth on my lung, and they thought it was cancer. I got tested for everything. I had tubes up my nose. It was scary."

Like Isringhausen, Guillen will be given antibiotics, too.

"He will probably be feeling much better in two weeks," Storey said. "The day you start taking antibiotics, the amount of infected bacteria actually in your system starts decreasing. But he will need to take antibiotics for a long time. This is the kind of bacteria that is difficult to eradicate."

Guillen came to the Mariners on July 31, 1998, along with right-hander Freddy Garcia and left-hander John Halama in a trade that sent Randy Johnson to the Houston Astros. Guillen became Seattle's regular shortstop last winter, after Rodriguez left as a free agent to go to the Texas Rangers.

He's been a key player for the Mariners this season, particularly in the field, where he committed only 10 errors in 140 games. He's batting .259 with five home runs and 53 RBIs.

By Jim Cour