A deranged nutjob slashed a Danish tourist in the face in an apparently random attack on the Upper West Side Wednesday morning, according to sources.

The screwball was caught on camera dashing after the 55-year-old victim on West 86th Street off Columbus Avenue around 10:40 a.m., before he came up from behind and slashed the man across the left ear and cheek, the sources said.

He then allegedly sprinted off back the way he’d come without a word.

The suspect was wearing a gray t-shirt, black athletic shorts, and sneakers, according to sources.

It’s unclear what he used as a weapon.

It’s also unclear what set off the slasher — he and victim didn’t appear to have exchanged words before the random attack, sources said.

Footage of the attack shows the victim walking calmly with a group of friends down the street, apparently completely at ease before the attacker sprints after them and then away.

The victim was treated at St. Luke’s Hospital by EMS for non-life-threatening injuries.

It comes as Manhattan was shaken this week by a string of violent stabbings carried out across Manhattan Monday by a single mad man, who left three people dead in the bloody rampage.

The suspect, 51-year-old Ramon Rivera, admitted to the hours-long spree that stretched from the west side all the way to the East River.

He was caught on camera calmly putting on a sweatshirt and gloves before unleashing the bloodbath.

Rivera had a documented history of mental health issues, and had been released from custody just a month ago on supervised release for a non-bail eligible petit larceny charge — which he received the same day he was sprung for time-served on a separate burglary charge.