Both youngsters penned new deals this week.
Edu told the club's website: "It's two young players, but different cases. Bukayo came through the academy and I think we did the right process with him - 100 per cent right. So he started with the first team just training, then he came into training even more, then started to be on the bench, then started to play 15 minutes, 20 minutes of games, then he became a very important player for the squad.
"So the process with him was brilliant. This process is the one we are working really hard on in the club to get it even more with the players. So that's very important for everybody and to send a message to everybody about the way we are working.
"Martinelli is a young player, different process but a very nice case as well. We bought Martinelli when he was 17, he didn't come from the academy, but we planned with him to start with our under-23s and then, because he's such a talented player in the pre-season he proved how he could be in the first team, as with Bukayo.
"Be on the bench, training with the first team to be in the squad, then he proved as well to be an important player as well so it's two different cases but we are really, really happy to have the possibility to renew and to be with them for a much longer period."