A student faces jail after admitting posting offensive comments on Twitter about the on-pitch collapse of footballer Fabrice Muamba.
Liam Stacey was arrested after his tweets were reported to police by Twitter users from across Britain, including former England striker Stan Collymore.
Stacey, 21, spent Sunday night in custody and was brought before magistrates in Swansea on Monday, where he admitted incitement to racial hatred. He was released on bail on condition that he stayed off Twitter and other social networking sites and will be sentenced next week. Stacey was told he could be jailed.
The swiftness of the arrest demonstrates how seriously police forces are taking the posting of potentially criminal comments on social networking sites by so-called "trolls".
Bolton Wanderers midfielder Muamba suffered a cardiac arrest during his team's FA Cup sixth round tie at Tottenham on Saturday night.
Lisa Jones, prosecuting, said: "Fabrice Muamba collapsed on the pitch and was believed to have died. Shortly after, Stacey posted on Twitter: "LOL, Fuck Muamba. He's dead."
Jones said other Twitter users criticised Stacey, prompting him to post a series of other offensive and racist comments.
Swansea magistrates heard that police around Britain had Stacey's comments reported to them by users including Collymore.
The court heard Stacey tried to claim his account had been hacked. He also tried to delete his page.
He texted a friend to say: "I said something about Muamba that I shouldn't have and tweeted back to some people who abused me. Getting police on me now, which isn't good at all."
Police arrested him on Sunday in Swansea. When interviewed, Stacey said he was drunk after drinking since early afternoon on Saturday while watching the Wales v France Six Nations rugby match.
He told police: "I was at the bar when I heard what had happened to Muamba. I don't know why I posted it. I'm not racist and some of my friends are from different cultural backgrounds."
Stacey, a biology undergraduate, was close to tears as the evidence was given about his tweets. The case was adjourned for reports to be prepared.
He was told that all sentencing options would be considered, including custody.
Muamba remained in a critical but stable condition on Monday morning
The Guardian 20.3.12