Despite a growing body of research on English-medium instruction (EMI), little is known about how actual EMI lecturers' language practices support L2 learning, specifically key psycholinguistic processes such as learner comprehension and output. This paper presents a classroom-centred study of the L2 learning opportunities found in the EMI lecturers' input. More specifically, it compares the presence of discourse features and strategies supporting students' input comprehension and output in a series of EMI classes taught by an English L1 lecturer and an English L2 lecturer at a Catalan university. The results show that both lecturers employ a variety of strategies to foster comprehensible input and student participation in their classes, with a clear bias in favour of the former. The English L1 lecturer provides more support to comprehensible input than his English L2 counterpart, who is keener on student participation. The profile of the students might have prompted the use of different discourse strategies, as well as the lecturers' beliefs on the nature of L2 scaffolding in EMI. We argue for the importance of developing research-informed EMI teacher training programmes revolving around discipline-specific language awareness and reflective cycles.