Deniz Undav has yet to really get going for VfB Stuttgart this season. Lothar Matthäus has a theory as to why that might be.

During an appearance on Sky90 on Sunday evening, the German national team's record appearance holder suggested VfB Stuttgart forward Deniz Undav may be feeling the weight of his new responsibility as captain.

"That is how it looks, at least, because he no longer has that lightness about him. He has lost his smile. Perhaps he is thinking too much," Matthäus explained. He argued against immediately taking the captain's armband away from Undav, but added: "But perhaps they did him no favour by giving it to him, because he is too preoccupied with himself."

Since taking over the captaincy from midfielder Atakan Karazor for the current season, Undav has gone through a minor dip in form. The 30-year-old has scored just once in 11 competitive appearances across all competitions in 2026/27 and has yet to score in seven Bundesliga appearances.

Undav's form is also part of the reason Stuttgart sit only 15th in the table. They have taken just six points from seven matches, most recently losing 3-2 to Borussia Mönchengladbach, who were bottom of the table and had yet to earn a point.

What next for Deniz Undav and VfB Stuttgart?

Matthäus called the defeat against Gladbach "the next setback" for Undav and VfB Stuttgart. "Of course, a great deal has gone on in his head over the past two years. Where has he come from? What has he achieved? All of Germany are talking about him: the saviour who will score the goals for Germany to make them world champions. Then, all of a sudden, he is captain. That was a lot for him to take in."

As captain, Undav now has "a special responsibility for the team. Not as much as a coach, admittedly, but as captain you do have things that can distract you from what you have done well for years," Matthäus explained.

Stuttgart and Undav face SC Paderborn in the DFB Cup on Wednesday. The following Saturday, coach Sebastian Hoeneß's team visit Bayer 04 Leverkusen in the Bundesliga.