Comedian Tracy Morgan will have to wait another four weeks before doctors can assess any longterm damage to his cognitive health following his horrific car crash in June (14).

The former 30 Rock star was hospitalised with a broken leg, nose and several ribs after the limousine he was travelling in was hit by a Wal-Mart truck, killing his good friend James 'Jimmy MACk' MCNair and leaving Morgan and two other passengers in a critical condition.

He was released from a rehabilitation facility in July (14) and has continued to undergo physiotherapy sessions at his New Jersey home, but the actor's attorney, Benedict P. Morelli, reveals Morgan, who is relying on a wheelchair to get around, still faces a long road to recovery both physically and in terms of his mental abilities and processes.

Morelli tells New Jersey's The Star-Ledger, "He's really having a tough time. He's making incremental progress. But they'll have to wait another month before they assess him cognitively."

Morelli's comments come three weeks after he publicly dismissed reports suggesting Morgan is "doing great", insisting the statement was far from accurate.

Morgan is currently suing Wal-Mart store executives for negligence amid allegations driver Kevin Roper's bosses should have known he had been awake for more than 24 hours at the time of the crash. Roper has pleaded not guilty to charges of vehicular homicide and assault by auto.