Adult acute ischemic stroke patients due to primary medium vessel occlusions (distal M2/M3 segments of the middle cerebral artery, A1/A2/A3 segments of the anterior cerebral artery, and P1/P2/P3 segments of the posterior cerebral artery confirmed by CTA/MRA, and responsible for the signs and symptoms of acute ischemic stroke) with baseline National Institutes of Health Stroke Scale (NIHSS) ≥6 or NIHSS 3-5 with disabling symptoms will be enrolled in this trial. We use perfusion imaging to select subjects and the enrolled patients have target mismatch profile on CTP or MRI+PWI (ischemic core volume <70mL, mismatch ratio>1.2, mismatch volume >10mL). If neither MRI or CT perfusion is available at the site, an ASPECTS/PC-ASPECTS of 8 or more on NCCT /MRI-DWI will be used.We will randomly assign eligible patients to receive tenecteplase (at a dose of 0.25 mg per kilogram of body weight; maximum dose, 25 mg) or standard medical treatment 4.5 to 24 hours after the time that the patient was last known to be well (including after stroke on awakening and unwitnessed stroke). The primary outcome is the proportion of patients with an mRS score ≤ 1 at 90 days.