The 40-year-old Monrovia resident arrived in Nigeria's mega-city on Sunday and was admitted to hospital on Tuesday suffering from severe vomiting and diarrhoea, said Yewande Adesina, the special adviser on health for the Lagos state government.
The patient was "detained for possible Ebola infection while blood samples were sent to the Virology Reference Laboratory in Lagos as well as to the World Health Organisation (WHO) in Dakar," he said.
"Results are still pending. Presently the patient's condition is stable and he is in recovery," Adesina told journalists. "The diarrhoea and vomited have stopped. He is still under isolation."
The patient traveled from Monrovia to Lagos via Togo's capital Lome, Adesina said.
The WHO has recorded more than 900 cases of Ebola in the epidemic that has raged across West Africa in recent months, but this is the first suspected case to emerge in Nigeria since the outbreak began.
Liberia has recorded 172 cases of the disease, including 105 deaths.
The epidemic is the worst-ever since the virus first emerged in 1976 in what is now the Democratic Republic of Congo.
The Lagos government has begun rolling out an emergency response in a bid to contain any potential spread of the virus across the congested city of more than 20 million people, with poor sanitation and health infrastructure.