Algorithmic approach to link adaptation for IEEE 802.11 networks such as Automatic Rate Fallback (ARF) is known to suffer from the inability to differentiate between collision and channel-induced error. In this paper, we propose a novel algorithm called COLA that overcomes the shortcoming and achieves near-optimal throughput over wide range of channel and load conditions. The result is significant since the throughput is achieved without any hardware support. Moreover, COLA does not require any optional or extra-protocol mechanisms support, either, such as RTS/CTS exchange, Clear Channel Assessment (CCS), and promiscuous channel monitoring. Finally, the COLA algorithm has a short critical path of just 10 instructions, and it is free of heuristic parameters, which will facilitate practical use.