Despite their recent slide, Watford have impressed in their first season back in the top flight and might fancy a cup run, while Newcastle's main focus is escaping the drop in the next four months.
No win in three since Christmas and two straight defeats mean that Watford come into this match not exactly high on confidence.
However, all three matches were against so-called big boys, with a 2-2 draw at Chelsea followed by crushing late defeats at home - both by a 2-1 scoreline - against Tottenham Hotspur and Manchester City.
Watford fans would not have been happy to see top-scorer Ighalo seemingly issuing a come-and-get-me plea to Manchester United by saying that it was his dream to play at Old Trafford like childhood heroes Dwight Yorke and Andy Cole, but a sale this month is still unlikely.
The Hornets, who have never won the FA Cup, were beaten 3-0 at Chelsea in last year's third round and their best run in recent times was nine years ago when they got to the semi-finals before losing to Manchester United.
Recent form: WWWDLL
Watford are still ninth with 29 points and how Newcastle would like to be part of that impressive top-half cluster with the likes of West Ham United, Crystal Palace and Stoke City.
Steve McClaren's side have lost three in a row - the longest losing streak in the Premier League - and lie in the bottom three after 20 games of the season.
All three defeats have been by a 1-0 scoreline, last time going down at Arsenal, and the Magpies have managed just one goal in four games since impressive back-to-back wins over Liverpool and Tottenham Hotspur at the start of December.
Goals have been a problem all season long and a new striker seems to be McClaren's number one priority this month in the transfer window, with French duo Loic Remy and Alexandre Lacazette both linked with January moves.
Newcastle, six-time winners of the competition, have a poor recent FA Cup record, losing at the first hurdle the last four years and losing six of their last seven third-round contests.
Recent form: WWDLLL
It seems unlikely that both Deeney and Ighalo will start and that could mean a debut for summer signing Obbi Oulare, who has appeared on the bench five times in the Premier League for the Hornets.
Watford are almost injury-free, but the same cannot be said of Newcastle.
McClaren has several key players out injured and he might not be able to rotate his squad as much as he would like.
Watford possible starting lineup:
Arlauskis; Anya, Prodl, Cathcart, Holebas; Abdi, Guedioura, Behrami, Jurado; Deeney, Ibarbo
Newcastle possible starting lineup:
Darlow; Janmaat, Lascelles, Mbemba, Dummett; Thauvin, De Jong, Tiote, Gouffran; Toney, Mitrovic
Head To Head
Ighalo scored twice inside the opening half-hour at St James' Park in September as Watford won 2-1 in the first Premier League meeting for eight years between the two. The pair meet again in two weeks' time for the reverse.
The last time these two met in the FA Cup was in 1989 when Watford came through 1-0 at the fourth time of asking in the third replay after three straight draws (0-0, 2-2, 0-0).
We say: Watford 3-1 Newcastle
With a 12-point buffer to Newcastle in the drop zone, it is hard to imagine Watford getting sucked into a relegation battle in the second half of the season unless perhaps some key players are poached this month. Therefore a cup run is a very realistic aim for the Hornets and they might just be more up for it than the Magpies.