Wireless local area networks (WLANs) have been globally deployed for years. Today, most WLANs adopt IEEE 802.11 distributed coordination function (DCF) for stations to share the medium. IEEE 802.11 DCF employs contention-based channel access, and as generally known, collision will happen when multiple stations launch transmissions simultaneously. However, from physical layer perspective, if the signal strength of one transmission is much higher than that of others, then the access point (AP) will be able to decode the transmission. This is called capture effect. Capture effect has the potential to improve the contention efficiency. In this paper, we propose Differentiated-Received-Power Transmit Power Control (DRP-TPC), which exploits capture effect to improve the contention efficiency. With DRP-TPC, each STA configures the transmit power, such that the received power at the AP side will meet a pre-specified requirement. DRP-TPC properly sets the received-power requirements, and thus, when multiple STAs launch transmissions simultaneously, the AP will still be able to decode the transmission with the best received signal strength. Simulation results show that, DRP-TPC outperforms the conventional TPCs in saturated throughput and medium access delay.