Calling All-In's with Marginal hands vs shortstack LAGS

[n4rf]

Take this scenario: Villain is 30/25/3.5

Full Tilt No-Limit Hold'em, $0.10 BB (5 handed) Full Tilt Converter Tool from FlopTurnRiver.com (Format: 2+2 Forums)

UTG ($4.55)
MP ($10)
Button ($10.95)
Hero ($9.75)
BB ($5.20)

Preflop: Hero is SB with 9[img]/images/graemlins/diamond.gif[/img], A[img]/images/graemlins/diamond.gif[/img].
<font color="#CC3333">UTG raises to $0.35</font>, <font color="#666666">2 folds</font>, <font color="#CC3333">Hero raises to $1.35</font>, <font color="#666666">1 fold</font>, <font color="#CC3333">UTG raises to $4.9 (All-In)</font>, Hero...


Basically my move here was a semi-bluff, but at the same time against an opponent like this I believe I have/had the best hand. When he comes over the top of me, might it still hold true (that I can possibly have the best hand) or do I have to fold this every time?

I know A9 is not exactly a great hand, so how would this differ with a hand like AJ,A10,KQ, or even lower pockets (VS this specific opponent).