Signalling issues are causing major delays for commuters hoping to reach Flemington Racecourse before Winx jumps the gates in the Turnbull Stakes.
Commuters aiming to reach the city from from Melbourne's southeast suburbs were forced to wait for replacement buses following the signalling breakdown late Saturday morning.
Lengthy delays are being experienced despite Metro announcing the recent reopening of the Alamein, Belgrave, Lilydale and Glen Waverley lines after an earlier suspension.
The incident created flow-on disruptions to trams on routes 16, 70, 72 and 75.
Some passengers were told there had been a car on the railway tracks.
Trains have now returned but are experiencing delays, after replacement buses were used to shuttle commuters between Camberwell and Parliament.
Lengthy delays and backlogs are also being reported at Southern Cross for passengers trying to reach Flemington Racecourse as superstar mare Winx seeks her 21st straight win soon after 3pm.