Isak, who completed a British-record £125m transfer to Liverpool on deadline day, was an unused substitute in his nation's 2-2 draw with Slovenia. 

The former Newcastle United striker took to the pitch for the first time since May after his transfer stand-off with the Magpies, coming on late in the second half. 

But Isak, who replaced Anthony Elanga for the final 18 minutes, was unable to make an impact as Sweden slumped to defeat courtesy of two first-half goals from Kosovo. 

Elvis Rexhbecaj bundled the ball past Robin Olsen for the opener in the 26th minute before Kosovo captain Vedat Muriqi sealed the victory three minutes before the break. 

Substitute Lindon Emerllahu was sent off in the first minute of stoppage time for a second bookable offence, but there was too little time for Sweden to fight back.

The result leaves Sweden third in Group B, five points adrift of leader Switzerland, whose first-half blitz against Slovenia sealed a comfortable 3-0 win on the same day. 

Nico Elvedi put the Swiss ahead with just 18 minutes on the clock, with the host doubling its advantage soon after through Breel Embolo's header from another set-piece. 

New Nottingham Forest signing Dan Ndoye concluded the scoring five minutes after Embolo's finish, but Croatia and Denmark also enjoyed fine victories in their clashes. 

Denmark captain Pierre-Emile Hojbjerg led by example in his nation's 3-0 win away to Greece, picking up two assists for Mikkel Damsgaard and Andreas Christensen. 

Ahead of his potential Serie A debut this weekend, Rasmus Hojlund got himself on the scoresheet in the 81st minute to keep the Danes at the summit of Group C. 

Croatia, meanwhile, maintained its perfect start to qualifying after thrashing Montenegro, which had Andrija Bulatovic sent off late in the first half, 4-0 at Stadion Maksimir. 

Kristijan Jakic netted his first international goal with a stunning strike from distance, before Andrej Kramaric, an Edvin Kuc own-goal and Ivan Perisic sealed the triumph.