|Mexican drug lord Joaquin "El Chapo" Guzman is being held in a prison in Ciudad Juarez following his recapture last year after he escaped from a maximum-security prison|
One of Guzman's lawyers, Jose Refugio Rodriguez, told AFP that the Sinaloa drug cartel leader was "very serene" as he waits for the decision by a court in Mexico City.
The foreign ministry gave the green light to Guzman's extradition in May, but the former most wanted man won a temporary injunction in June, which the judge must decide whether to make permanent or strike down.
"We hope that the result will be favorable," Refugio Rodriguez said, adding that if the judge rules on Monday, Guzman's defense team would only be notified the next day.
If the judge approves the extradition, Guzman would have 10 days to appeal to a higher court of appeals, which would take several weeks to rule, the lawyer said, warning that he would take the case to the Supreme Court if necessary.
A US government official told AFP on condition of anonymity that Guzman could be in US custody before the end of the year. He faces charges ranging from murder to drug distribution in courts in Texas and California.
Guzman was captured in February 2014 after evading police for 13 years, but he escaped a year later from the Altiplano maximum-security prison near Mexico City under a 1.5-kilometer (one-mile) tunnel, humiliating President Enrique Pena Nieto.
After he was recaptured in January in his northwestern home state of Sinaloa, he was sent back to the same prison.
But he was abruptly transferred in May to another prison in Ciudad Juarez, a city bordering Texas that was once the scene of brutal turf wars between his gang and a local cartel.
Pena Nieto had balked at extraditing Guzman before his escape in July 2015, preferring to put him on trial in Mexico.
But after he was recaptured, the president ordered the attorney general's office to speed up the extradition process.
Refugio Rodriguez said his client's health has "deteriorated a lot" while in prison.
"He's doing very badly. He's isolated. He lost a lot of hair because he takes a lot of medicine. He lives in constant physical stress," the lawyer said.
Guzman's extradition would set up a major trial in the United States for a man whose cartel has been accused of murdering countless people in Mexico while providing tons of cocaine and other drugs to addicts in the United States.
But another Guzman lawyer, Andres Granados, told AFP that if his client is "judged according to the law, he won't be extradited this year or during the six-year term" of Pena Nieto.