CLEVELAND (AP) – Cavaliers All-Star forward LeBron James was expected to spend a second night in the hospital Thursday after undergoing tests for chest pain the team said was from a strained muscle.

On the advice of Cavaliers doctors, James was admitted to the Cleveland Clinic on Wednesday after pain on the left side of his chest worsened after practice. He underwent a series of tests Thursday, and general manager Danny Ferry said James was likely to be kept overnight because he had a fever.

Ferry said tests on James have not shown anything abnormal, and his understanding is that James’ heart “is not an issue.”

“They’re going to test everything,” Ferry said. “There are no red flags.”

James said he doesn’t know how he got the injury, which team doctors initially diagnosed as a strained left pectoral muscle. The third-year pro said he woke up in pain Tuesday morning in Pittsburgh. He had scored 16 points the previous night in the Cavs’ preseason opener against Washington.

The Cavaliers did not reveal James’ hospital stay until Thursday afternoon when he missed practice.

Following Wednesday’s light workout at Quicken Loans Arena, James continued to be bothered by stiffness and soreness in his chest area. At the Cavaliers’ urging, the 20-year-old was taken to the hospital.

“Just as a precaution, we wanted to have tests to make sure he checks out well,” Ferry said. “All the test results we have back so far have been good and there is nothing to be concerned about. Every indication is that it is a muscle injury.”

The Cavaliers have a home preseason game Friday night against Philadelphia, and travel to Milwaukee on Saturday.

James can’t pinpoint how he got hurt.

“I don’t know where it came from,” he said on Wednesday when he winced during the portion of practice open to the media. “I don’t remember getting elbowed in the chest or pushed. It was something I never felt before.”

With their regular-season opener several weeks away, the Cavaliers aren’t taking any chances with James, their franchise player.

“We just want to make sure our guys are healthy,” Ferry said. “He’s resting now, we told him to take it easy.”

James has been remarkably durable during his first two seasons in the NBA.

As a rookie, he missed three games with a sprained right ankle. Last season, he missed only two games with a sprained left ankle.

James was expected to miss much more time after he had his left cheek bone broken by Houston center Dikembe Mutombo, who nailed James with an elbow Dec. 29. But James was fitted with a plastic protective mask and didn’t miss any games while wearing the mask for six weeks.

In his second season, he led the league in minutes per game (42.4) and minutes played (3,388) while becoming just the fifth player in league history to average 27 points, 7 rebounds and 7 assists for a season.

AP-ES-10-13-05 2137EDT