The Denmark player is said to be stable in hospital after reportedly suffering a cardiac arrest when he collapsed in Denmark's Euro 2020 match against Finland yesterday.
Lizzie founded the Danny Jones Defibrillator Fund in honour of her husband to raise funds for equipment and screening for local and professional sports clubs.
She posted on social media: “Sending love and strength to Christian and his family today.
“A very real and very upsetting event to watch but highlighting the importance of quick CPR and early defibrillation.”
She added that the Danny Jones Defibrillator fund can help anyone needing a defibrillator.
Welsh International Rugby League player Danny died aged 29 after suffering a cardiac arrest during a match in May 2015.
Post mortem results showed that he died of cardiomyopathy - an inherited condition leading to the thickening of the cardiac muscles.
Cardiomyopathy can be diagnosed following an echocardiogram screening which was not available to Danny.
As well as spearheading the push for long-term screening in the rugby league capacity, Lizzie’s charity has been extended to include other sporting and community groups and has raised over £150,000 to date, screening over 2,000 people in a variety of sports.
It has allowed over 80 defibrillators to be distributed to sporting clubs with grant assistance.
It is reported 75 per cent of players and supporters are now covered by a defibrillator during matches with the ambition to reach 100 per cent, a target which includes professional and grassroots teams.
Professional singer Lizzie was awarded an MBE for services to Rugby League and charity in 2020.
For more information about the fund and how to support its work, visit https://www.dannyjonesdefibfund.co.uk/ .