Sporting Lisbon came from 2-0 down to draw 2-2 at home to 10-man Estoril in the Liga Sagres on Saturday, as Porto were also held.
Visitors Estoril led through Steven Vitoria's 45th-minute penalty in the match at Estadio Jose Alvalade, with Luis Leal doubling the lead shortly before the hour-mark.
The away side's prospects of holding their advantage took a blow when they lost Goncalo to a second yellow card in the 59th minute.
And the comeback began when Estoril's Anderson Luis put through his own put in the 75th minute.
It was left for star striker Ricky van Wolfswinkel to bag the equaliser with seven minutes remaining.
Also on Saturday, Porto were fortunate to escape with a point from their visit to Rio Ave.
They had led through Miguel Lopes' goal on 32 minutes at Estadio do Rio Ave Futebol Clube.
The hosts levelled through Tarantini in the 78th minute and the same man put Rio Ave ahead when he struck again just seven minutes later.
Porto declined to go home empty handed, with Jackson Martinez on hand to make it 2-2 on 89 minutes.