  In the minimal Universal Extra Dimension (mUED) model, the second
Kaluza-Klein (KK) gluon $g^{(2)}$ has loop-induced vertices with the standard
model quarks, mediated by the first KK modes of the quark and the gluon/Higgs
boson. With a top quark pair, this vertex is enhanced by the cooperation of the
strong coupling of a gluon and the large Yukawa coupling of a top quark,
leading to substantial branching ratio of $Br(g^{(2)} \to t \bar{t}) \approx
7%-8%$. As the $g^{(2)}$ coupling with two gluons appears via dimension-6
operator, $q\bar{q}\to g^{(2)}\to t\bar{t}$ is the golden mode for the mUED
model. Hence the best channel is the $t\bar{t}$ resonance search in $p\bar{p}$
collisions. The recent Tevatron data at $\sqrt{s}=1.96$ TeV with an integrated
luminosity of 8.7 fb$^{-1}$ are shown to give the first direct bound on the
$g^{(2)}$ mass above 800 GeV. The implication and future prospect at the LHC
are discussed also.
