With hours to go for the start of the sixth edition of the PSL in Karachi, Peshawar Zalmi captain Wahab Riaz and coach Daren Sammy have been forced into three-day quarantine after a breach of Covid-19 protocols. It is understood that they met a person outside the team's biosecure bubble on Friday.

A Lahore Qalandars player, meanwhile, has tested positive for Covid-19, with symptoms, and has been sent into isolation for 10 days.

Zalmi are set to play their opening match on Sunday against the Qalandars, and the team is in discussions to decide who their stand-in captain will be in Wahab's absence. Shoaib Malik is understood to be an option, but Zalmi are assessing other options too.

The breach came three days after the PCB had briefed players, support staff and match officials to "religiously follow" all Covid-19 protocols. Each PSL franchise has its own Covid compliance officer, who is responsible for testing, implementation of protocols, sanitisation, and players' temperature checks. The whole process is bring regulated by the event doctor.

"The PCB is disappointed that two members of one of the sides showed carelessness and violated the bio-secure bubble protocols by coming into contact with a person who was not part of the bubble," the PCB said in a statement issued in the wee hours of Saturday. "As reiterated previously, the health and safety of all individuals associated with Pakistan Super League 6 is of paramount importance to the PCB and the event. All players, player support personnel, match officials and family members are once again reminded to diligently follow the PCB Covid-19 Protocols as the PCB will not allow anyone to affect the integrity and credibility of the tournament."

Wahab and Sammy will now need to return two negative tests during their three-day quarantine before they can re-enter the bio-secure bubble in accordance with re-entry protocols. The infected player who tested positive had earlier shown symptoms and will likely miss the Karachi leg as he will require two negative tests in the next 10 days. He has been isolated from his team and will be reintegrated after clearing his Covid-19 tests and a fitness assessment.

"This is an extremely critical phase in the tournament as the sides are in the process of assembling in Karachi," said Dr. Sohail Saleem, the PCB's director of medical and sports sciences. "As such, it is important that each side provides a detailed and thorough briefing to their players on the dos and don'ts during the competition so that there are no misunderstandings and the event cannot only commence successfully but progress in a safe and secure environment.

"The PCB Covid-19 Protocols are simple and straightforward but stringent. We implemented these successfully during the domestic and international matches, and there is no reason why we cannot ensure these are followed during the Pakistan Super League."

GMT 1045 The story was updated with details about the bubble breach.

Umar Farooq is ESPNcricinfo's Pakistan correspondent