Paulo Retre scored a first-half brace as Sydney FC held on to beat Adelaide United 2-1 and move nine points clear at the top of the A-League table.

In the week that he signed a contract extension with the league leaders, Retre's double put Sydney in command at Netstrata Jubilee Stadium before Riley McGree pulled one back.

Adelaide are without a win in 11 league meetings with Sydney but came close to opening the scoring five minutes in when Ryan Strain hit the post with an impressive strike.

The hosts, who had their advantage cut to six points following Melbourne City's narrow win over Western United on Friday, grew into the match and scored a quickfire double. 

Paul Izzo saved Harry Van der Saag's header but the ball fell invitingly for Retre to steer in, and the midfielder scored a second six minutes later with a low shot from 18 yards.

McGree, returning from a month out, got the final touch to James Troisi's cross to reduce the arrears before half-time, but the visitors could not find a leveller after the interval. 

Wellington Phoenix beat Central Coast Mariners 2-1 at Sky Stadium in Saturday's other A-League clash to extend their unbeaten run to eight matches.

English strikers Gary Hooper and David Ball gave the hosts a two-goal lead, but Luke DeVere scored an own goal and Wellington required Stefan Marinovic to produce a fine save to preserve the three points.