Trainer Archie Alexander is delighted to have Craig Williams aboard last-start country winner Plus Effronte at Sandown as the champion jockey bids to secure a sixth Melbourne premiership.

Williams has wrested the lead from apprentice Beau Mertens in the past two weeks and takes a two-win advantage into the penultimate city meeting of the season on Wednesday.

Mertens has five rides at Sandown while Williams has a full book of eight including Plus Effronte who is among the main chances in the Christmas in July @ Highways Handicap, a benchmark-64 over 1400m.

"He was the one who was actually pretty keen to get on her for this race," Alexander said.

"That's a massive help. Every jockey is always trying in every race but you know there will be extra fire in his belly.

"And Craig Williams trying to win a premiership - you couldn't get better than that."

Plus Effronte has won two of her eight starts and makes her city debut after winning at Donald on July 8.

"We've actually always really liked her but she's had a few issues along the way," Alexander said.

"It seems like maybe we're jumping the gun but we feel now we might have got to the bottom of those and her work has been really good.

"Last time was an impressive win so we think she deserves a chance in town and it's probably the best midweek option she'll ever get."

Alexander is still undecided whether Supreme Harmony will run in the Le Pine Funerals Handicap (1800m) but fellow three-year-old Buena Veloz faces his first city test in the Ladbrokes Odds Boost Multi Handicap (1600m) after winning a benchmark-58 at Echuca last start.

"We think he deserves his chance," Alexander said.

"If he doesn't get to that midweek city level, so be it and we'll know where we stand. But I think he can."

Alexander has taken the blinkers off Buena Veloz, who will be ridden by apprentice Ben Allen, in a bid to get him to jump with the field having been slowly away in recent starts.

Ballarat-based Alexander has trained 34 winners this season, double last season, including nine in town and the stable's runners are closing in on $1 million prize money for 2016/17.

"We couldn't have dreamed for a better 12 months," he said.