Labour will be smarting somewhat after losing a second by-election to the Liberal Democrats in one of its strongholds.
In itself, the lost by-election barely makes a dent in Labour's grip on power in Sunderland. The party still holds 65 of the 75 seats on the council, and yesterday's win for the Lib Dems brings their total to just three councillors.
But the fact it is the second surprise victory for the party over Labour in little over a year, in a city where the Lib Dems have had a poor presence for decades, will pose some worry for Labour.
Until Wearside Lib Dems leader Niall Hodson was elected to represent in the last round of council elections in 2016, the party had been wiped out in Sunderland. It hadn't held a seat on the city council for five years.
The Liberal Democrats last stand had been in the Millfield ward, where their sole councillor Paul Dixon was voted out in 2011.
After his defeat on election night, Mr Dixon launched a stinging attack on then-party leader Nick Clegg's unpopular decision to form a coalition government with David Cameron's Tories following the 2010 General Election.
However, the party's fortunes and popularity appear to be in resurgence in Wearside. Councillor Hodson's victory in 2016 saw them claim back Millfield, and a by-election the following January saw Stephen O’Brien snatch the contested seat in Sandhill.
There were no full council elections last year, so Councillor Haswell's victory in Pallion yesterday means Labour haven't seen a victory in the polls in Sunderland for 18 months. though, again, that amounts to just two seats.
Jeremy Corbyn silenced many of his critics with Labour's General Election performance in June, but there is still a sizable section of voters who have turned away from the party since the left-winger took control.
This may well have played a part in the resurgence of support the Lib Dems in Sunderland.
The Lib Dem victories also show voters appear to have forgiven the party for getting into bed with the Tories, perhaps listening to claims that life would have been worse-off under the Tories had they not been a softening presence in the Coalition Government.
Voters may also have been looking for a new voice of opposition in the city, and been won over by Lib Dem's message in Wearside. Councillor Hodson and his party colleagues have been making their presence felt.
Sunderland Conservatives have been beaten back to their historic strongholds in recent years. The Tories once appeared to be proving a real challenge for Labour in the city, taking seats in all corners of Wearside. But their popularity waned again in Sunderland once the party returned to national government.
Brexit has seen the Ukip vote collapse nationwide. Though the pro-Europe stance of the Lib Dems nationally makes it seem unlikely they will have picked up too many votes from Ukippers.
Whether the Lib Dems manage to capitalise on their victories and gain more seats in Sunderland remains to be seen.
By-elections tend to attract smaller turnouts than scheduled council elections, and lower turnouts tend to work against Labour in its heartlands. The next round of council elections on May 3, where a third of council seats will be contested, will prove a bigger test.
What's for sure, though, is that Councillors Hodson, O’Brien and Haswell will be out for more blood - and Labour will be fighting back.