Though the OP question has been answered the same way I am about to answer it, I just wanted to throw some evidence in:
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As we see from that link, Madara is indirectly admitting Obito is stronger. I would guess this since Madara states he cannot wait any longer/he can't wait anymore... as well as Obito anticipating him before he is able to use his "trump-card". I would say those 2 statements alone denote that Madara is afraid and that Obito is RIGHT NOW stronger than he is... even if Madara won't say it himself (which let's face it, isn't really his style anyway.)