The 24-year-old-midfielder underwent emergency surgery and had his spleen removed after being stretchered off in Tuesday night’s 2-0 National League North win at Gainsborough Trinity.
Walsall-born Smith, signed this summer from Romulus, was sent on as a substitute in the 70th minute. But five minutes later, he accidentally clashed with an opponent.
After receiving treatment, he was then taken to Lincoln County Hospital.
A club spokesman said, “Lee has had his operation. It was successful, but he is still expected to be in intensive care for the next 24 to 48 hours.
“The surgeon was pleased with how the operation went. Lee is in intensive care, but no longer on a ventilator. He is able to talk with his family, who are by his side.”