(;SZ[19]AW[cc]AW[dd]AW[cf]AW[cq]AW[dp]AW[cn]AW[ro]AW[qn]AW[qk]AW[qh]AB[pd]AB[rp]AB[qo]AB[pp]AB[np]AB[ic]AB[fc]AB[db]LB[nc:A]LB[pb:B]GM[1]FF[4]AP[Drago:1.42]L[nc]L[pb] (;W[nc]TR[oc];B[oc]TR[nd];W[nd];B[qf]TR[kc];W[kc];B[ld]TR[lc];W[lc];B[nb]TR[mb];W[mb];B[ob]TR[ke];W[ke];B[rn]LB[nc:1]LB[oc:2]LB[nd:3]LB[qf:4]LB[kc:5]LB[ld:6]LB[lc:7]LB[nb:8]LB[mb:9]LB[ob:10]LB[ke:11]LB[rn:12]C[White 1 may seem like a normal approach move, but approaching inside Black's sphere of influence is often a risky strategy. Black 2 and 4 are good responses. If white extends to 5, black plays a forcing move with 6, then secures a large profit in the corner with 10 in sente. Black 12 is now a thick move that removes all the bad aji in the corner and destabilizes the white stones on the right.]) (;W[pb];B[nc]TR[nb];W[nb];B[mc]TR[mb];W[mb];B[lc]TR[qd];W[qd];B[qe]TR[qc];W[qc];B[pf]TR[rn];W[rn]LB[pb:1]LB[nc:2]LB[nb:3]LB[mc:4]LB[mb:5]LB[lc:6]LB[qd:7]LB[qe:8]LB[qc:9]LB[pf:10]LB[rn:11]C[White's invasion at 1 is the proper move. If Black 2, White settles his stones in the corner in sente with the sequence to 9. After black makes shape with 10, white secures his stones on the right side with 11. This move leaves black with bad aji in the corner. Moreover, the strong positions white has on the left and right limit the power black has with his wall. Now navigate the 'wrong' o17 variation for an explication to it's shortcomings, if you haven't accidentally done so already...RIGHT]))