Shagufta Kausar and her husband Shafqat Emmanuel, a poor Christian couple from the town of Gojra in Pakistan's Punjab region, will attend a final hearing at Lahore's High Court after being on death row since 2014.
They were arrested for sending blasphemous text messages that insulted the Prophet Muhammad to a local Imam.
Shagufta's brother Joseph said he visited the couple in jail where they told him the confession was extracted under torture.
'He told me the policeman hit [Shafqat] so hard that his leg was broken,' Joseph said.
He added that the conviction has taken a toll on the couple's four children who 'wish to see their parents again'.
As to the accusations against his family, Joseph, who asked to remain anonymous, said he thought the couple were illiterate so doubted they could have written the messages.
He told the BBC that his sister worked as a caretaker in a Christian school and that Shafqat was out of work, owing to a disability, at the time of their arrest.
Blasphemy is a hugely sensitive issue in Pakistan and any conviction warrants a death sentence.
Even unproven allegations of insulting Islam can lead to assassinations and lynchings from furious mobs.
Though no-one has yet been hung for the crime, those who are set free face the wrath of extremist vigilantes.
The couple's lawyer, Saif ul Malook - who represented Asia Bibi and helped overturn her conviction in 2018 - said the couple's case was stronger than Bibi's but that judges are often 'fearful' to overturn rulings.
Some high-profile justices have been assassinated for releasing people accused of the crime.
'They have been used to target religious minorities, pursue personal vendettas and carry out vigilante violence.'
According to Malook, the couple believes one of their Christian neighbours bought a sim card in Shagufta's name and sent the messages to the Imam to settle a score.
The acquittal last October of Bibi, a Christian who had spent more than eight years on death row for blasphemy, provoked violent protests across Pakistan.
Bibi now lives in Canada with her family.
