Bayer Leverkusen are navigating a defining summer that is reshaping their squad on multiple fronts, with the club's resolve in the transfer market and a significant tactical shift under new head coach Carles Martinez setting the tone for the season ahead.

The clearest signal of Leverkusen's ambition came when the club rejected a reported €60m plus €5m bonus offer from Arsenal for centre-back Jarell Quansah, telling the Premier League champions the 23-year-old is simply not for sale. Quansah arrived from Liverpool for €35m just last summer and immediately became a first-team fixture, making 44 appearances across all competitions. With his contract running until 2030, Leverkusen have made their position plain, and the rejection of what would have been a €25m profit underlines how seriously they are building for the long term.

While Quansah stays, captain Robert Andrich appears set to leave. According to reports, the club has told the 31-year-old midfielder he has no real future under Martinez, whose switch to a back four leaves little room for Andrich's profile. A player who made 46 appearances last season and wore the armband after Granit Xhaka's departure, Andrich is now weighing his first move abroad to protect his chances of returning to the Germany squad under Jürgen Klopp.

Adding further intrigue, a potential return for former fan favourite Moussa Diaby has stalled, with Inter Milan entering the race for the winger from Al-Ittihad. Leverkusen head into their DFB-Pokal opener at Wehen Wiesbaden on August 22 carrying genuine momentum from preseason, including a 2-1 friendly win over Newcastle United.