Juventus defender Stephan Lichtsteiner has said he does not know when he will be able to play again after being referred for tests on his heart following breathing difficulties.

Switzerland international Lichtsteiner was replaced at half-time in Juve's 1-1 draw with Frosinone and taken to hospital, where he was kept under observation.

He returned to training on Monday but club doctors ordered him to see a heart specialist for further tests, ruling him out of the 2-0 Champions League win over Sevilla on Wednesday.

The 31-year-old wrote on his Facebook page: "At the moment, I am still not allowed to play because I need to overcome some more medical tests.

"It's going to take a bit of time and patience, but I can't wait to get back on the field. Thanks for all your get-well wishes. Hugs, Steph."

Ciao a tutti, nell' ultimo post sono stato un pò troppo ottimista.Al momento non potrò ancora giocare visto che dovrò... Posted by Stephan Lichtsteiner on Wednesday, 30 September 2015

Lichtsteiner watched as Juve moved clear at the top of their Champions League group thanks in part to a record-equalling goal from Alvaro Morata.

Morata scored for a fifth consecutive Champions League appearance, emulating the 1995-96 achievement of Alessandro Del Piero.

"We're delighted, but now I have to work on scoring also in Serie A," the Spaniard said.

"We're pleased with this win. My understanding with [Paulo] Dybala obviously still has to improve. We've not played together for a long time, but we've got a great relationship.

"We're friends, we eat out together with our families, and you can see this [closeness] on the field.

"We need to carry on working to do better in the league -- but what counted tonight was winning, so I'm happy."