A 39-year-old woman was grabbed as she jogged along the canal towpath between the city centre and Kirkstall on Wednesday morning.
That followed an incident in which a 23-year-old woman was dragged into bushes next to the River Aire off Redcote Lane in Kirkstall on Monday evening.
Both women escaped shaken but relatively unscathed.
Det Chief Insp Elizabeth Belton, who is investigating the two attacks, said: “There is nothing as is stands to specifically link this incident with the one at Redcote Lane but given the relative proximity of the scenes and the relatively short space of time in which they have occurred it is appropriate that we consider if there is any link.”
The 23-year-old was leaving Pure gym, off Kirkstall Road, when she was attacked at about 5.50pm on Monday.
She escaped after fighting back and is believed to have scratched her attacker on his face.
The predator ran off after a man rode past on a bicycle. He has since come forward to speak to police.
The attacker was described as white, aged in his twenties, scruffy, about 5ft 6ins and skinny. He was wearing a dark coloured tracksuit with a zip-up top.
Detective Chief Inspector Elizabeth Belton, of West Yorkshire Police Homicide and Major Enquiry Team, said: “This was clearly a very frightening experience for the victim and we can only speculate as to what might have happened had she not fought back and her attacker been disturbed.
“We are investigating this incident as an attempted serious sexual assault and it is vital that we identify and trace her attacker at the earliest opportunity.
“We believe she scratched this man’s face during the incident and I am appealing for anyone who knows someone who fits the general description who has had scratch marks to their face since Monday teatime.
“We have already spoken to a number of witnesses but we are still keen to hear from anyone who was in the area in the time around the incident who saw a man fitting the description of the attacker.”
In the second incident, the 39-year-old victim was running near to a lock on the stretch of canal towpath between the A58 inner ring road and Viaduct Road in Kirkstall when she was grabbed.
She escaped and called police.
DCI Belton added: “That investigation is at an early stage and we are still in the process of interviewing the victim.
“We would like to hear from anyone who was on the canal towpath this morning and witnessed the incident or saw this man in the area.”
The attacker was described as white, 5ft 9ins tall, aged in his late twenties, with brown hair and a scruffy stubble beard. He was wearing a black hooded top.
Chief Superintendent Paul Money, Leeds District Commander, said: “We fully appreciate that incidents of this nature will understandably cause concern in the community. We are conducting extensive enquiries into both incidents and officers from the local neighbourhood policing teams are mounting increased patrols in both areas to provide visible reassurance.”
Anyone with any information is asked to contact the homicide and major enquiry team via 101 or call the independent crime-fighting charity Crimestoppers anonymously on 0800 555 111.