Yemen newspaper Al-Moatamar reported that the former Egypt manager was taken to a hospital in the Thai capital after suffering a Brain Attack.
It is not yet clear whether Saleh would be able to lead the Gulf side in the decisive second round return game.
The first leg in Sanaa ended in a 1-1 draw.
Japan coach in intensive care
Ironically, Japan coach Ivica Osim is in a critical condition as well after suffering a Heart Stroke, the Japan FA confirmed.
The Bosnian coach collapsed while climbing stairs at his home on Friday, and JFA technical director Kozo Tajima conceded that his condition is unstable.
"That he is still in an intensive care unit means we can't be optimistic," JFA technical director told a news conference on Saturday.
"He hasn't gotten worse and he hasn't gotten better. He's unconscious.
"The only thing the soccer world wants is for him to become well enough to be able to leave the intensive care unit."
Osim, 66, was not able to watch his side's 4-3 penalty shootout victory in the Asian Cup quarter-finals this summer for health reasons.
He followed the shootout news from the dressing room as he claimed later that 'it was bad for his heart'.
نرشح لكم
أشرف صبحي: هدفنا الوصول لنهائي كأس أمم إفريقيا
انتخابات الأهلي – الغزاوي: التنمية والاستثمار هما هدف المرحلة المقبلة للمجلس
صلاح عاد للتسجيل ولكن.. ليفربول يغرق بالخسارة الرابعة على التوالي
مدرب إيجل نوار: الأهلي كان قويا رغم الطرد
أشرف صبحي: ربما يتم حل أزمة أرض الزمالك في أكتوبر أو منحه أرضا بديلة
مصدر من الأهلي لـ في الجول: ننوي الاحتجاج على الحكم.. ومطلب عاجل في المجموعات
قائمة بيراميدز – استمرار غياب رمضان صبحي أمام التأمين الإثيوبي
عضو اتحاد الكرة: نعمل على الاتفاق مع مدرب أجنبي للمنتخب الأولمبي











