The invention relates to a method of automatic adjustment of a single-input-port and single-output-port tunable matching circuit, for instance a single-input-port and single-output-port tunable matching circuit coupled to an antenna of a radio transceiver. The invention also relates to an automatic tuning system using this method. The reactance of each adjustable impedance device of the tunable matching circuit is determined by at least one tuning control signal. In addition to the begin symbol and the end symbol, a flowchart of a tuning sequence comprises: a process generating initial values of the tuning control signals, which uses an open-loop control scheme using one or more real quantities depending on an impedance seen by the target port; and a process generating subsequent values of the tuning control signals, which uses a closed-loop control scheme and an extremum-seeking control algorithm.